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An HTML element is an individual component of an HTML document or web page, once this has been parsed into the Document Object Model. HTML is composed of a tree of HTML nodes, such as text nodes. Each node can have HTML attributes specified. Nodes can also have content, including other nodes and text. Many HTML nodes represent semantics, or meaning. For example, the title
node represents the title of the document.
HTML documents are delivered as "documents".[note 1] These are then parsed, which turns them into the Document Object Model (DOM) internal representation, within the web browser.[note 2][note 3]
Presentation by the web browser, such as screen rendering or access by JavaScript, is then performed on this internal model, not the original document.
Early HTML documents, and to a lesser extent today, were largely invalid HTML and riddled with syntax errors. The parsing process was also required to "fix-up" these errors, as best it could. The resultant model was often not correct (i.e. it did not represent what a careless coder had originally intended), but it would at least be valid, according to the HTML standard. A valid model was produced, no matter how bad the "tag soup" supplied had been. Only in the rarest cases would the parser abandon parsing altogether.
"Elements" and "tags" are terms that are widely confused. HTML documents contain tags, but do not contain the elements. The elements are only generated after the parsing step, from these tags.[]
As is generally understood, the position of an element is indicated as spanning from a start tag, possibly including some child content, and is terminated by an end tag.[3] This is the case for many, but not all, elements within an HTML document.
As HTML is based on SGML,[4] its parsing also depends on the use of a DTD, specifically an HTML DTD such as that for HTML 4.01.[5][note 4] The DTD specifies which element types are possible (i.e. it defines the set of element types that go to make up HTML) and it also specifies the valid combinations in which they may appear in a document. It is part of general SGML behavior that where only one valid structure is possible (per the DTD), it is not generally a requirement that the document explicitly states that structure. As a simple example, the <p>
start tag indicating the start of a paragraph element should be closed by a </p>
end tag, indicating the end of the element. Also the DTD states that paragraph elements cannot be nested. The HTML document fragment:
<p>Para 1 <p>Para 2 <p>Para 3
can thus be inferred to be equivalent to:
<p>Para 1 </p><p>Para 2 </p><p>Para 3
(If one paragraph element cannot contain another, any currently open paragraph must be closed before starting another.)
Because of this implied behavior, based on the combination of the DTD and the individual document, it is not possible to infer elements from the document tags alone, but only by also using an SGML or HTML aware parser, with knowledge of the DTD.
SGML is complex, which has limited its widespread adoption and understanding. XML was developed as a simpler alternative. XML is similar to SGML, that can also use the DTD mechanism to specify the supported elements and their permitted combinations as document structure. XML parsing is simpler. The relation from tags to elements is always that of parsing the actual tags included in the document, without the implied closures that are part of SGML.[note 5]
In Macros HTML can be formed as XML, either through XHTML or through HTML5, the parsing of document tags as DOM elements is simplified. Once the DOM of elements is obtained, behavior beyond that point (i.e. screen rendering) is identical.[note 6]
%block;
vs. boxPart of this CSS presentation behavior is the notion of the "box model". This is applied to those elements that CSS considers to be "block" elements, set through the CSS display: block;
declaration.
HTML also has a similar concept, although different, and the two are very frequently confused. %block;
and %inline;
are groups within the HTML DTD that group elements as being either "block-level" or "inline".[7] This is used to define their nesting behavior: block-level elements cannot be placed into an inline context.[note 7] This behavior cannot be changed; it is fixed in the DTD. Block and inline elements have the appropriate and different CSS behaviors attached to them by default,[7] including the relevance of the box model for particular element types.
Note though that this CSS behavior can, and frequently is, changed from the default. Lists with <ul><li> ...
are %block;
elements and are presented as block elements by default. However, it is quite common to set these with CSS to display as an inline list.[8]
In the HTML syntax, most elements are written with a start tag and an end tag, with the content in between. An HTML tag is composed of the name of the element, surrounded by angle brackets. An end tag also has a slash after the opening angle bracket, to distinguish it from the start tag. For example, a paragraph, which is represented by the p
element, would be written as
<p>In the HTML syntax, most elements are written ...</p>
However, not all of these elements require the end tag, or even the start tag, to be present. Some elements, the so-called void elements or empty elements, do not have an end tag. A typical example is the br
element, which represents a significant line break, such as in a poem or an address. A void element's behavior is predefined, and it cannot contain any content or other elements. For example, an address would be written as
<p>P. Sherman<br>42 Wallaby Way<br>Sydney</p>
When using an XHTML DTD, it is required to open and close the element with a single tag. To specify that it is a void element, a /
is included at the end of the tag (not to be confused with the /
at the beginning of a closing tag).
<p>P. Sherman<br />42 Wallaby Way<br />Sydney</p>
HTML attributes are specified inside the start tag. For example, the abbr
element, which represents an abbreviation, expects a title
attribute within its opening tag. This would be written as
<abbr title="abbreviation">abbr.</abbr>
There are multiple kinds of HTML elements: void elements, raw text elements, and normal elements.
Void elements only have a start tag, which contains any HTML attributes. They may not contain any children, such as text or other elements. Often they are place holders for elements which reference external files, such as the image (<img />
) element. The attributes included in the element will then point to the external file in question.
Another example of a void element is the <link />
element, for which the syntax is
<link rel="stylesheet" href="fancy.css" type="text/css">
This <link />
element points the browser at a style sheet to use when presenting the HTML document to the user. Note that in the HTML syntax, attributes don't have to be quoted if they are composed only of certain characters: letters, digits, the hyphen-minus and the full stop. When using the XML syntax (XHTML), on the other hand, all attributes must be quoted, and a trailing slash is required before the last angle bracket:
<link rel="stylesheet" href="fancy.css" type="text/css" />
Raw text elements are constructed with:
<tag>
) marking the beginning of an element, which may incorporate any number of HTML attributes;</tag>
. In some versions of HTML, the end tag is optional for some elements. The end tag is required in XHTML.Normal elements usually have both a start tag and an end tag, although for some elements the end tag, or both tags, can be omitted. It is constructed in a similar way:
<tag>
) marking the beginning of an element, which may incorporate any number of HTML attributes;</tag>
.HTML attributes define desired behavior or indicate additional element properties. Most attributes require a value. In HTML, the value can be left unquoted if it doesn't include spaces (name=value
), or it can be quoted with single or double quotes (name='value'
or name="value"
). In XML, those quotes are required. Boolean attributes, on the other hand, don't require a value to be specified. An example is the checked
for checkboxes:
<input type=checkbox checked>
In the XML syntax, though, the name should be repeated as the value:
<input type="checkbox" checked="checked" />
Informally, HTML elements are sometimes referred to as "tags" (an example of synecdoche), though many prefer the term tag strictly in reference to the markup delimiting the start and end of an element.
Element (and attribute) names may be written in any combination of upper or lower case in HTML, but must be in lower case in XHTML.[9] The canonical form was upper-case until HTML 4, and was used in HTML specifications, but in recent years, lower-case has become more common.
HTML elements are defined in a series of freely available open standards issued since 1995, initially by the IETF and subsequently by the W3C.
During the browser wars of the 1990s, developers of user agents (e.g. web browsers) often developed their own elements, some of which have been adopted in later standards. Other user agents may not recognize non-standard elements, and they will be ignored, possibly causing the page to be displayed improperly.
In 1998, XML (a simplified form of SGML) introduced mechanisms to allow anyone to develop their own elements and incorporate them in XHTML documents, for use with XML-aware user agents.[10]
Subsequently, HTML 4.01 was rewritten in an XML-compatible form, XHTML 1.0 (eXtensible HTML). The elements in each are identical, and in most cases valid XHTML 1.0 documents will be valid or nearly valid HTML 4.01 documents. This article mainly focuses on real HTML, unless noted otherwise; however, it remains applicable to XHTML. (See HTML for a discussion of the minor differences between the two).
Since the first version of HTML, several elements have become outmoded, and are deprecated in later standards, or do not appear at all, in which case they are invalid (and will be found invalid, and perhaps not displayed, by validating user agents).[11]
At present, the status of elements is complicated by the existence of three types of HTML 4.01 / XHTML 1.0 DTD:
The first Standard (HTML 2.0) contained four deprecated elements, one of which was invalid in HTML 3.2. All four are invalid in HTML 4.01 Transitional, which also deprecated a further ten elements. All of these, plus two others, are invalid in HTML 4.01 Strict. While the frame elements are still current in the sense of being present in the Transitional and Frameset DTDs, there are no plans to preserve them in future standards, as their function has been largely replaced, and they are highly problematic for user accessibility.
(Strictly speaking, the most recent XHTML standard, XHTML 1.1 (2001), does not include frames at all; it is approximately equivalent to XHTML 1.0 Strict, but also includes the Ruby markup module.)[12]
A common source of confusion is the loose use of deprecated to refer to both deprecated and invalid status, and to elements which are expected to be formally deprecated in future.
Since HTML 4, HTML has increasingly focused on the separation of content (the visible text and images) from presentation (like color, font size, and layout).[13] This is often referred to as a separation of concerns. HTML is used to represent the structure or content of a document, its presentation remains the sole responsibility of CSS style sheets. A default style sheet is suggested as part of the CSS standard, giving a default rendering for HTML.[14]
Behavior (interactivity) is also kept separate from content, and is handled by scripts. Images are contained in separate graphics files, separate from text, though they can also be considered part of the content of a page.
Separation of concerns allows the document to be presented by different user agents according to their purposes and abilities. For example, a user agent can select an appropriate style sheet to present a document by displaying on a monitor, printing on paper, or to determine speech characteristics in an audio-only user agent. The structural and semantic functions of the markup remain identical in each case.
Historically, user agents did not always support these features. In the 1990s, as a stop-gap, presentational elements (like <b>
and <i>
) were added to HTML, at the cost of creating problems for interoperability and user accessibility. This is now regarded as outmoded and has been superseded by style sheet-based design; most presentational elements are now deprecated.[15]
External image files are incorporated with the img
or object
elements. (With XHTML, the SVG language can also be used to write graphics within the document, though linking to external SVG files is generally simpler.)[16] Where an image is not purely decorative, HTML allows replacement content with similar semantic value to be provided for non-visual user agents.
An HTML document can also be extended through the use of scripts to provide additional behaviors beyond the abilities of HTML hyperlinks and forms.
The elements style
and script
, with related HTML attributes, provide reference points in HTML markup for links to style sheets and scripts. They can also contain instructions directly.
script
and style
may either link to shared external documents, or contain embedded instructions. (The link
element can also be used to link style sheets.)script
can occur at any point in the document body.noscript
element provides alternative content where appropriate; however, it can only be used as a block-level element.<html>...</html>
<head>...</head>
<body>...</body>
<base/>
href
and other links in the document. Must appear before any element that refers to an external resource. HTML permits only one base
element for each document. The base
element has HTML attributes, but no contents.<basefont/> (deprecated)
font
elements. Deprecated in favor of style sheets.<isindex/> (deprecated)
isindex
could either appear in the document head or in the body, but only once in a document. See Forms.<link/>
<link rel="stylesheet" type="text/css" href="url" title="description_of_style">
[18]<link rel="next" href="url">
head
element may contain any number of link
elements. The link
element has HTML attributes, but no contents.meta
elements specify associative key-value pairs. In general, a meta element conveys hidden information about the document. Several meta tags can be used, all of which should be nested in the head element. The specific purpose of each meta
element is defined by its attributes.meta
elements can specify HTTP headers which should be sent by a web server before the actual content. For example, <meta http-equiv="foo" content="bar">
specifies that the page should be served with an HTTP header called foo
that has a value bar
.meta
element specifies name
and associated content
HTML attributes describing aspects of the HTML page. To prevent possible ambiguity, an optional third attribute, scheme
, may be supplied to specify a semantic framework that defines the meaning of the key and its value. For example, in <meta name="foo" content="bar" scheme="DC">
the meta
element identifies itself as containing the foo
element, with a value of bar
, from the DC or Dublin Core resource description framework.<object>...</object>
head
element, it could potentially be used to extract foreign data and associate it with the current document.<script>...</script>
src
attribute.[19] Also usable in the document body to dynamically generate either both block or inline content.<style>...</style>
<style type="text/css"> ... </style>
@import
directives of the form:
<style> @import url; </style>
[20]<title>...</title>
title
element must not contain other elements, only text. Only one title
element is permitted in a document.In visual browsers, displayable elements can be rendered as either block or inline. While all elements are part of the document sequence, block elements appear within their parent elements:
Conversely, inline elements are treated as part of the flow of document text; they cannot have margins, width or height set, and do break across lines.
Block elements, or block-level elements, have a rectangular structure. By default, these elements will span the entire width of its parent element, and will thus not allow any other element to occupy the same horizontal space as it is placed on.
The rectangular structure of a block element is often referred to as the box model, and is made up of several parts. Each element contains the following:
The above section refers only to the detailed implementation of CSS rendering and has no relevance to HTML elements themselves.
<p>...</p>
P
existed in HTML Tags, and was standardized in HTML 2.0; still current.<h1>...</h1>
<h2>...</h2>
<h3>...</h3>
<h4>...</h4>
<h5>...</h5>
<h6>...</h6>
h1
delimits the highest-level heading, h2
the next level down (sub-section), h3
for a level below that, and so on to h6
. They are sometimes referred to collectively as hn
tags, n meaning any of the available heading levels.<dl>...</dl>
DL
existed in HTML Tags, and was standardized in HTML 2.0; still current.<dt>...</dt>
DT
existed in HTML Tags, and was standardized in HTML 2.0; still current.<dd>...</dd>
DD
existed in HTML Tags, and was standardized in HTML 2.0; still current.<ol>...</ol>
type
attribute can be used to specify the kind of marker to use in the list, but style sheets give more control. The default is Arabic numbering. CSS: list-style-type: foo
. HTML attribute: , in either case, replacing foo
with one of the following:
A
for A, B, C...a
for a, b, c...I
for I, II, III...i
for i, ii, iii...1
for 1, 2, 3...OL
existed in HTML Internet Draft 1.2, and was standardized in HTML 2.0; still current.<ul>...</ul>
list-style-type: foo
. The default marker type is disc
, other values are square
, circle
and none
.UL
existed in HTML Tags, and was standardized in HTML 2.0; still current.<li>...</li>
ol
) or unordered (ul
) lists.LI
existed in HTML Tags, and was standardized in HTML 2.0; still current.<dir>...</dir> (deprecated)
<ul>
.DIR
existed in HTML Tags, and was standardized in HTML 2.0; deprecated in HTML 4.0 Transitional; invalid in HTML 4.0 Strict.<address>...</address>
ADDRESS
existed in HTML Tags, and was standardized in HTML 2.0; still current.<article>...</article>
<aside>...</aside>
<blockquote>...</blockquote>
cite
attribute may give the source, and must be a fully qualified Uniform Resource Identifier.q
) element.BLOCKQUOTE
existed in HTML Internet Draft 1.2, and was standardized in HTML 2.0; still current. See blockquote element for more information.<center>...</center> (deprecated)
<div>
or another element with centering defined using style sheets.<del>...</del>
<div>...</div>
<figure>...</figure>
figcaption
.<figcaption>...</figcaption>
<footer>...</footer>
<header>...</header>
<hr/>
<ins>...</ins>
<main>...</main>
<menu>...</menu>
<ul>
list.MENU
existed in HTML Tags, and was standardized in HTML 2.0; deprecated in HTML 4.0 Transitional; invalid in HTML 4.0 Strict; but then redefined in HTML5.<nav>...</nav>
<noscript>...</noscript>
<pre>...</pre>
pre
, white-space should be rendered as authored. (With the CSS properties: {white-space: pre; font-family: monospace;}
, other elements can be presented in the same way.) This element can contain any inline element except: image (IMG
), object (OBJECT
), big font size (BIG
), small font size (SMALL
), superscript (SUP
), and subscript (SUB
).PRE
existed in HTML Internet Draft 1.2, and was standardized in HTML 2.0; still current.<section>...</section>
div
in that it is only used to contain sections of a page, which the W3C defines as a group of content with a similar theme.<script>...</script>
SCRIPT
is not itself either a block or inline element; by itself it should not display at all, but it can contain instructions to dynamically generate either both block or inline content.Inline elements cannot be placed directly inside the body
element; they must be wholly nested within block-level elements.[24]
<a>...</a>
href
,[26] the anchor becomes a hyperlink to either another part of the document or another resource (e.g. a webpage) using an external URL. Alternatively (and sometimes concurrently), with the name
or id
HTML attributes set, the element becomes a target. A Uniform Resource Locator can link to this target via a fragment identifier. In HTML5, any element can now be made into a target by using the id
attribute,[27] so using <a name="foo">...</a>
is not necessary, although this way of adding anchors continues to work.example.com
could be turned into a target by writing
=Table of contents=
<a href="http://example.com#contents">see contents</a>
<a href="#contents">contents, above</a>
title
may be set to give brief information about the link:
<a href="URL" title="additional information">link text</a>
title
is displayed in a tooltip or in some other manner. Some browsers render alt text the same way, although this is not what the specification calls for.A
existed in HTML Tags, and was standardized in HTML 2.0; still current.<abbr>...</abbr>
<abbr title="abbreviation">abbr.</abbr>
<acronym>...</acronym> (deprecated)
abbr
element, but marks an acronym:
<acronym title="Hyper-Text Mark-up Language">HTML</acronym>
<dfn>...</dfn>
DFN
existed in HTML Internet Draft 1.2, and was fully standardized in HTML 3.2; still current.<em>...</em>
EM
existed in HTML Internet Draft 1.2, and was standardized in HTML 2.0; still current.<strong>...</strong>
STRONG
existed in HTML Internet Draft 1.2, and was standardized in HTML 2.0; still current.These elements are useful primarily for documenting computer code development and user interaction through differentiation of source code (<code>
), source code variables (<var>
), user input (<kbd>
), and terminal output (<samp>
).
<code>...</code>
code example
). Conventionally rendered in a mono-space font.CODE
existed in HTML Internet Draft 1.2, and was standardized in HTML 2.0; still current.<kbd>...</kbd>
KBD
existed in HTML Internet Draft 1.2, and was standardized in HTML 2.0; still current.<samp>...</samp>
SAMP
existed in HTML Internet Draft 1.2, and was standardized in HTML 2.0; still current.<var>...</var>
VAR
existed in HTML Internet Draft 1.2, and was standardized in HTML 2.0; still current.As visual presentational markup only applies directly to visual browsers, its use is discouraged. Style sheets should be used instead. Several of these elements are deprecated or invalid in HTML 4 / XHTML 1.0, and the remainder are invalid in the current draft of XHTML 2.0. The current draft of HTML5, however, re-includes <s>
, <u>
, and <small>
, assigning new semantic meaning to each. In an HTML5 document, the use of these elements is no longer discouraged, provided that it is semantically correct.
<b>...</b>
{font-weight: bold}
. '''...'''
usually has the same effect in visual browsers, as well as having more semantic meaning, under HTML 4.01.<b>
has its own meaning, distinct from that of <strong>
. It denotes "text to which attention is being drawn for utilitarian purposes without conveying any extra importance and with no implication of an alternate voice or mood."[28]B
existed in HTML Internet Draft 1.2, and was standardized in HTML 2.0; still current.<i>...</i>
{font-style: italic}
. <em>...</em>
usually has the same effect in visual browsers, as well as having more semantic meaning, under HTML 4.01.<i>
has its own semantic meaning, distinct from that of <em>
. It denotes "a different quality of text" or "an alternative voice or mood"--e.g., a thought, a ship name, a binary species name, a foreign-language phrase, etc.[29]I
existed in HTML Internet Draft 1.2, and was standardized in HTML 2.0; still current.<u>...</u>
{text-decoration: underline}
. Deprecated in HTML 4.01. Restored in HTML5.<u>
element denotes "a span of text with an unarticulated, though explicitly rendered, non-textual annotation, such as labelling the text as being a proper name in Chinese text (a Chinese proper name mark), or labelling the text as being misspelt." The HTML5 specification reminds developers that other elements are almost always more appropriate than <u>
and admonishes designers not to use underlined text where it could be confused for a hyper-link.[30]U
existed in HTML Internet Draft 1.2, was standardized in HTML 3.2 but was deprecated in HTML 4.0 Transitional and was invalid in HTML 4.0 Strict. Reintroduced in HTML5.<small>...</small>
{font-size: smaller}
<small>
element denotes "side comments such as small print."[31]<s>...</s>
<strike>
.<s>
element denotes information that is "no longer accurate or no longer relevant", and is not to be confused with <del>
, which indicates removal/deletion.[32]S
was deprecated in HTML 4.0 Transitional (having not appeared in any previous standard), and was invalid in HTML 4.0 Strict. Reintroduced in HTML5.<big>...</big> (deprecated)
{font-size: larger}
<strike>...</strike>
{text-decoration: line-through}
)STRIKE
was standardized in HTML 3.2; deprecated in HTML 4.0 Transitional; invalid in HTML 4.0 Strict.<tt>...</tt> (deprecated)
{font-family: monospace;}
)TT
existed in HTML Internet Draft 1.2, and was Standardized in HTML 2.0; not supported[33] in HTML5. Possible replacements: <kbd>
for marking keyboard input, <var>
for variables, <code>
for computer code, <samp>
for computer output.[33]<font>...</font>
<font [color=<var>color</var>] [size=<var>size</var>] [face=<var>face</var>]>...</font>
color
attribute (note the American spelling), typeface with the face
attribute, and absolute or relative size with the size
attribute.<font color="green">text</font>
creates green text.<font color="#114499">text</font>
creates text with hexadecimal color #114499.<font size="4">text</font>
creates text with size 4. Sizes are from 1 to 7. The standard size is 3, unless otherwise specified in the <body> or other tags.<font size="+1">text</font>
creates text with size 1 bigger than the standard. <font size="-1">text</font>
is opposite.<font face="Courier">text</font>
makes text with Courier font.<font size="N">
corresponds to {font-size: Yunits}
(the HTML specification does not define the relationship between size N and unit-size Y, nor does it define a unit).<font color="red">
corresponds to {color: red}
<font face="Courier">
corresponds to {font-family: "Courier"}
<span>...</span>
<br/>
<bdi>...</bdi>
<bdo>...</bdo>
<cite>...</cite>
<data>...</data>
<del>...</del>
<ins>...</ins>
<del>
'd text. Typically rendered underlined: Inserted text.<ins>
and <del>
elements may also be used as block elements: containing other block and inline elements. However, these elements must still remain wholly within their parent element to maintain a well-formed HTML document. For example, deleting text from the middle of one paragraph across several other paragraphs and ending in a final paragraph would need to use three separate <del>
elements. Two <del>
elements would be required as inline element to indicate the deletion of text in the first and last paragraphs, and a third, used as a block element, to indicate the deletion in the intervening paragraphs.<mark>...</mark>
Standardized in HTML5.
<q>...</q>
blockquote
). Quote elements may be nested.<q>
should automatically generate quotation marks in conjunction with style sheets. Practical concerns due to browser non-compliance may force authors to find workarounds.cite
attribute gives the source, and must be a fully qualified URI.block-quote
) using style sheets. For example, with a suitable CSS rule associated with q.lengthy
:
<q class="lengthy">
An inline quotation of significant length (say 25 words, for example) goes here...</q>
<rb>...</rb>
<rp>...</rp>
<rt>...</rt>
<rtc>...</rtc>
<ruby>...</ruby>
<script>...</script>
<script>
is not itself either a block or inline element; by itself it should not display at all, but it can contain instructions to dynamically generate either both block or inline content.<sub>...</sub>
and <sup>...</sup>
{vertical-align: sub}
or {vertical-align: super}
.)<template>...</template>
<time>...</time>
<wbr/>
<applet>...</applet> (deprecated)
<object>
, as it could only be used with Java applets, and had accessibility limitations.<object>
are not consistent between different browsers.<area/>
<audio>...</audio>
src
attribute. Supported audio formats vary from browser to browser.<canvas>...</canvas>
<embed>...</embed>
object
tag, but then was added back into the HTML5 specification[41][42]<img/>
src
attribute specifies the image URL. The required alt
attribute provides alternative text in case the image cannot be displayed.[43] (Though alt
is intended as alternative text, Microsoft Internet Explorer 7 and below render it as a tooltip if no title
is given.[44]Safari and Google Chrome, on the other hand, do not display the alt attribute at all.)[45]img was proposed by Marc Andreessen and implemented in the NSCA Mosaic web browser.[46]<map>...</map>
<object>...</object>
type
attribute. This may be in any MIME-type the user agent understands, such as an embedded HTML page, a file to be handled by a plug-in such as Flash, a Java applet, a sound file, etc.<param/>
<source>...</source>
src
attribute in a way similar to the video
and audio
elements.<track>...</track>
<video>...</video>
src
attribute. Supported video formats vary from browser to browser.These elements can be combined into a form or in some instances used separately as user-interface controls; in the document, they can be simple HTML or used in conjunction with Scripts. HTML markup specifies the elements that make up a form, and the method by which it will be submitted. However, some form of scripts (server-side, client-side, or both) must be used to process the user's input once it is submitted.
(These elements are either block or inline elements, but are collected here as their use is more restricted than other inline or block elements.)
<form action="url">...</form>
<button>...</button>
<datalist>...</datalist>
option
s for use in form elements.<fieldset>...</fieldset>
<input/>
<button>
is preferred if possible (i.e. if the client supports it) as it provides richer possibilities.src
attribute.size
attribute specifies the default width of the input in character-widths. max-length
sets the maximum number of characters the user can enter (which may be greater than size).<isindex/> (deprecated)
isindex
could either appear in the document head or in the body, but only once in a document.<keygen>...</keygen>
<label for="id">...</label>
<legend>...</legend>
<meter>...</meter>
<option value="x">...</option>
select
list.<optgroup>...</optgroup>
<output>...</output>
<progress>...</progress>
<select name="xyz">...</select>
<textarea rows="8">...</textarea>
cols
(where a col is a one-character width of text) and rows
HTML attributes. The content of this element is restricted to plain text, which appears in the text area as default text when the page is loaded.The format of HTML Tables was proposed in the HTML 3.0 Drafts and the later RFC 1942 HTML Tables. They were inspired by the CALS Table Model. Some elements in these proposals were included in HTML 3.2; the present form of HTML Tables was standardized in HTML 4. (Many of the elements used within tables are neither block nor inline elements.)
<table>...</table>
<tr>...</tr>
<th>...</th>
<td>...</td>
<colgroup>...</colgroup>
<col>...</col>
<caption>...</caption>
<thead>...</thead>
<tbody>...</tbody>
<tfoot>...</tfoot>
thead
, this section may be repeated by the user agent if the table is split across pages (in printing or other paged media).Frames allow a visual HTML Browser window to be split into segments, each of which can show a different document. This can lower bandwidth use, as repeating parts of a layout can be used in one frame, while variable content is displayed in another. This may come at a certain usability cost, especially in non-visual user agents,[47] due to separate and independent documents (or websites) being displayed adjacent to each other and being allowed to interact with the same parent window. Because of this cost, frames (excluding the element) are only allowed in HTML 4.01 Frame-set. Iframes can also hold documents on different servers. In this case the interaction between windows is blocked by the browser. Sites like Facebook and Twitter use iframes to display content (plugins) on third party websites. Google AdSense uses iframes to display banners on third party websites.
In HTML 4.01, a document may contain a and a or a and a , but not both a and a . However, can be used in a normal document body.
<frameset>...</frameset> (deprecated)
rows
and cols
HTML attributes.<frame/> (deprecated)
frameset
. A separate document is linked to a frame using the src
attribute inside the frame
element.<noframes>...</noframes> (deprecated)
<iframe>...</iframe>
object
element, an inline frame can be the "target" frame for links defined by other elements, and it can be selected by the user agent as the focus for printing, viewing its source, and so on.In HTML, longdesc is an attribute used within the image element, frame element, or iframe element. It is supposed to be a URL[note 8] to a document that provides a long description for the image, frame, or iframe in question.[48] Note that this attribute should contain a URL, and not as is commonly mistaken, the text of the description itself.
Longdesc was designed to be used by screen readers to display image information for computer users with accessibility issues, such as the blind or visually impaired, and is widely implemented by both web browsers and screen readers.[49] Some developers object that [50] it is actually seldom used for this purpose, because there are relatively few authors who use the attribute, and most of those authors use it incorrectly, and have used this argument to recommend dropping longdesc.[51] The publishing industry has responded, advocating the retention of longdesc.[52]
<img src="Hello.jpg" longdesc="description.html">
Content of description.html
:
<br />
<p>This is an image of a two-layered birthday cake.</p>
...
Since very few graphical browsers support making the link available natively (Opera and iCab being the exceptions), it is useful to include a link to the description page near the img
element whenever possible, as this can also aid sighted users.
<img src="Hello.jpg" longdesc="description.html" /> [<a href=
"description.html" title="long description of the image">D</a>]
The following elements were part of the early HTML developed by Tim Berners-Lee from 1989-91; they are mentioned in HTML Tags, but deprecated in HTML 2.0 and were never part of HTML standards.
<listing>...</listing> (deprecated)
<plaintext/> (deprecated)
plaintext
does not have an end tag, as it terminates the markup and causes the rest of the document to be parsed as if it were plain text.plaintext
existed in HTML Tags; deprecated in HTML 2.0; invalid in HTML 4.0.<xmp>...</xmp> (deprecated)
<nextid/> (deprecated)
nextid
existed in HTML Tags (described as obsolete); deprecated in HTML 2.0; invalid in HTML 3.2 and later.This section lists some widely used obsolete elements, which means they are not used in valid code. They may not be supported in all user agents.
<blink>...</blink> (deprecated)
{text-decoration: blink}
(This effect may have negative consequences for people with photosensitive epilepsy;[56] its use on the public Internet should follow the appropriate guidelines.)blink
originated in Netscape Navigator and is mostly recognized by its descendants, including Firefox; deprecated or invalid in HTML 2.0 and later. Note that the replacement CSS tag, while standard, is not required to be supported.<marquee>...</marquee> (deprecated)
marquee
originated in Microsoft Internet Explorer; deprecated or invalid in HTML 4.01 and later.<nobr>...</nobr> (deprecated)
{white-space: nowrap;}
nobr
is a proprietary element which is recognized by most browsers for compatibility reasons; deprecated or invalid in HTML 2.0 and later.<noembed>...</noembed> (deprecated)
embed
or object
element.<!-- A Comment -->
A comment in HTML (and related XML, SGML and SHTML) uses the same syntax as the SGML comment or XML comment, depending on the doctype.
Unlike most HTML tags, comments do not nest.
The markup <!--Xbegin<!--Y-->Xend-->
will yield the comment Xbegin<!--Y
and the text Xend-->
after it.
Comments can appear anywhere in a document, as the HTML parser is supposed to ignore them no matter where they appear so long as they are not inside other HTML tag structures.
Comments can even appear before the doctype declaration; no other tags are permitted to do this.
However, not all browsers and HTML editors are fully compliant with the HTML syntax framework and may do unpredictable things under some syntax conditions. Defective handling of comments only affects about 5% of all browsers and HTML editors in use (IE6 accounting for most of this high percentage). Even then only certain versions are affected by comment mishandling issues.
There are a few compatibility quirks involving comments:
style
and script
elements are still sometimes surrounded by comment delimiters.<style> ... {comment tags} ...</style>
show up on screen. Other HTML editors may have this same defect.<object>
for the inevitable exception.
|section=
ignored (help)
|section=
ignored (help)
|section=
ignored (help)
|section=
ignored (help)
|section=
ignored (help)
...frames do present additional usability challenges that are unique to users with disabilities, particularly those who use screen readers.
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