In computing, an HTML element designates structure in an HTML document and a way of hierarchically arranging content. More specifically, an HTML element is an SGML element that meets the requirements of one or more of the HTML Document Type Definitions (DTDs). These elements have properties: both attributes and content, as specified (both allowable and required) according to the appropriate HTML DTD (for example, the HTML 4.01 strict DTD). Elements may represent headings, paragraphs, hypertext links, lists, embedded media, and a variety of other structures.

Syntactically HTML elements are constructed with: 1) a start tag marking the beginning of an element; 2) any number of attributes (and their associated values); 3) some amount of content (characters and other elements); and 4) an end tag. Many HTML elements include attributes in their start tags, defining desired behavior or signifying extra element properties. The end tag is optional for many elements; in a minimal case, an empty element has no content and requires no end tag. There are a few elements that are not part of any official DTDs, yet are supported by some browsers and used by some web pages. Such elements may be ignored or displayed improperly on browsers not supporting them.

Informally, HTML elements are sometimes referred to as "tags" (an example of synecdoche), though many prefer the term tag strictly in reference to the semantic structures delimiting the start and end of an element.

XHTML is the successor to HTML 4.01; XHTML 1.0 supports the same elements as HTML 4 and in most cases valid XHTML 1.0 documents will be valid or nearly valid HTML 4 documents. XHTML 1.0 migrates HTML from its SGML underpinnings to an XML foundation. Accordingly, the discussion of elements within this article focuses on the final SGML based HTML, version 4.01 (unless noted otherwise). However, to the extent that XHTML 1.0 elements remain indistinguishable to the HTML 4.01 elements, the discussion remains applicable (see HTML for a discussion of the minor differences in content between XHTML 1.0 and HTML 4.01).

Block-level and inline elements

HTML elements are classified as either block-level or inline (text-level).Block-level elementsHeadings, paragraphs, lists, or tables are "large" structures containing other blocks, inline elements, or text (but see nesting rules, below). They are typically displayed as independent "blocks" separated from other blocks by vertical space (margins).
Inline or text-level elementsHyperlinks, citations, quotations, or images are "small" structures that represent or describe small pieces of text or data. They may contain only text or other inline elements, and are typically displayed one after another on a line within the block that contains them.

(See "The global structure of an HTML document")

Nesting of elements

Many HTML elements can be nested, or contained within other HTML elements:

You rock

Nesting can be more complex:

King Louis said, L'état, c'est moi! (Wikipedia).

Nesting may be arbitrarily deep, but the elements must be closed in the reverse order that they were opened for the code to remain valid (this pattern is known as Last in, first out).Incorrect

Mary kissed Jimmy

Mary kissed Jimmy

Some block-level elements (e.g. paragraphs) may contain only inline elements, and some (e.g. forms, lists) must contain only block-level child elements, but most may contain either block-level or inline elements.

Document elements

Root elements provide the containers enclosing all other HTML elements. Every HTML page has these elements. The surrounding tags may be omitted. However, some utilities may not recognize or correctly handle the document if this is done.

…Delimit an HTML document (i.e. instead of an XML or another class document). The HTML element takes the attributes lang for the primary language for the document (such as en for English) and a profile for a URI specifying metadata for the document (rarely used). The only contents allowed in an HTML element is one head element and one body element. (See Frames, below, for an exception where body is not used.)

…Delimit the header section of the document, which contains information about the page. The head element basically contains the metadata for the document. There are seven possible head elements including a meta element for extensible specification of metadata.

…Delimit the body section of the document, which contains the displayed content of the page.

These root elements are arranged as follows:Any of the various head related elements arranged in any order and occurring any number of times except base and title that can only occur once each. Title is the only required head element.


At least one of either a block element or a script element must occur, (though any number may occur), arranged in any order to suit the meaning and also typically the presentation of the document. The ins and del elements are also permissible within the body element when used as block level elements. The other block elements are: paragraph (p), heading (h1...h6), block quotation (blockquote), ordered list (ol), unordered list (ul), definition list (dl), division (div), no script support (noscript), form (form), table (table), fieldset (fieldset), and address (address). No other HTML elements are valid within the body element.

Head elements

Define a document title. This element is required in every HTML and XHTML document. Different user agents may make use of the title in different ways. Web browsers typically display it in the title bar when the window is open, and in the task bar when it is minimized. It may become the default filename when saving the page, Search engines' web crawlers may pay specific attention to the words used in the title element. The title element must not contain any nested tags (in other words it can't contain any other elements). Only one title element is permitted in a document.

Specifies a base URL for all relative 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 attributes, but no contents.

Specifies links to other documents, such as 'previous' and 'next' links, or alternate versions . An HTML head may contain any number of link elements. The link element has attributes, but no contents. A common use is to link to external stylesheets, using the form:

(deprecated)Specifies a base font size, typeface and color of the document. Used together with font elements. Deprecated in favor of stylesheets.

Used to add JavaScript or other scripts to the document. The script code may be literally typed between the script tags and/or it may be in a separate resource whose URL is specified in script's optional src attribute.

Specifies a style for the document, usually:
The CSS statements may be literally typed between the style tags and/or it may be in separate resources whose URLs are specified in @import directives such as:.

Use for including generic objects within the head. Though rarely used as a head element, this could potentially be used to extract foreign data, relevant to the document, and associate this data with the current document.

Can be used to specify author, publication date, expiry date, page description, keywords and any other metadata not provided through the other head elements and attributes. Because of their generic nature, meta elements specify key-value pairs.
In one form, meta elements can specify HTTP headers which should be sent before the actual content when the HTML page is served from web server to client. For example:

This example specifies that the page should be served with an HTTP header called 'foo' that has a value 'bar'
In the general form, a meta element specifies name and associated content attributes describing aspects of the HTML page. To prevent possible ambiguity, a third optional scheme attribute may be supplied to specify a semantic framework that defines the meaning of the key and its value. For example

In this example, the meta element identifies itself as containing the 'foo' element, with a value of 'bar', from the DC or Dublin Core resource description framework.

Inline

Inline elements can't be placed directly inside the body element for valid HTML. They must be wholly nested within block-level elements (see block elements below).

General phrase elements

…Emphasis (conventionally displayed in italics)

…strong emphasis (conventionally displayed bold). An oral user agent may use different voices for emphasis.

…A quotation containing only inline elements (for quotations containing block level elements see blockquote below). Quote elements may be nested. By the specification, the author should not include quotation marks. Rather, quotation marks - including nested quotation marks - should be rendered through stylesheet properties or the browser's default stylesheet. Practical concerns due to browser non-compliance may force authors to find work-arounds. The cite attribute gives the source, and must be a fully qualified URI.
Note: within semantic HTML, the display of a lengthy inline quotation as an indented block should be handled through stylesheet presentation. One method is to use an XSLT to select quotation elements exceeding a certain length (in terms of characters or words, etc.) for indented block presentation. An alternative, using Cascading Stylesheets, requires some presentational markup to manually classify the element as a lengthy quotation. For example:
An inline quotation of significant length (say 25 words, for example) goes here....

…A citation. Reference for a quote or statement in the document.

…Defining first instance of a term

…Contains an abbreviation, like abbr.

…Similar to the abbr element, but contains an acronym, like HTML.

Computer code phrase elements

These elements are useful primarily for documenting computer code development and user interaction through differentiation of source code (), source code variables (), user input (), and terminal output ().

…A code snippet. Conventionally rendered in a monospace font: Code snippet.


…Sample output (from a program or script)


…Keyboard - text to be entered by the user


…Variable


Special inline elements



… …Create subscript or superscript text: Equivalent CSS: {vertical-align: sub} or {vertical-align: super}


…Deleted text. Typically rendered as a strikethrough: Deleted text.


…Inserted text. Often used to markup replacement text for 'd text. Typically rendered underlined: Inserted text.
Note, both ins and del elements may 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 designate the deletion of text in the first and last paragraphs, and a third, used as a block element, to designate the deletion in the intervening paragraphs.



(deprecated)The :isindex element requires server side support for indexing documents. Visually presents a one-line text input for keyword entry. When submitted, the query string is appended to the current URL and the document is displayed with these keywords highlighted. Generally if the server supports this feature it will add the isindex elements to documents without author intervention.


Links and anchors



…Creates an element that becomes a hyperlink with the href (hypertext reference) attribute set to a URL; additionally the attribute title may be set to a hover box text, some informative text about the link:
link textIn most graphical browsers, when the cursor hovers over the link, the cursor typically changes into a hand with a stretched index finger and the extra information pops up, not in a regular window, but in a special "hover box", typically similar to a Tooltip, which disappears when the cursor is moved away. Some browsers render alt text the same way, though this is technically incorrect.
Then again (and sometimes concurrently), the element becomes an anchor with the name attribute set, which preceded by a number sign ' # ', and appended to the URL, acts as a link target (a "document fragment"), typically causing a Web browser to scroll directly to that point of the page. Any element can be made into an anchor by using the id attribute, so using is not necessary.
See also:link


Images and objects



Includes an image with the src attribute, the required alt attribute provides alternative text in case the image can't be displayed. Alt is intended as alternative text, although Microsoft Internet Explorer renders it as a tooltip if no title is given; the title attribute is the tooltip text.



Specifies a line-break.
Specifies a client-side image map.


Specifies an area in the map.

Includes an object in the page of the type specified by the type attribute. This may be in any MIME-type the Web browser understands, such as an embedded page, code to be handled by a plug-in such as Flash, a Java applet, a sound file, etc.
This element may only appear inside an object element. Using attributes such as name and value, each sets a parameter for the object. Examples include width, height, font, background colour, etc, depending on what has been exposed in this way by the object's developers.
… (proprietary)Calls a plug-in handler for the type specified by the type attribute. Used for embedding Flash files, sound files, etc. This is a proprietary Netscape extension to HTML;