HTML: Difference between revisions

Revision as of 21:22, 24 February 2025

Revision as of 02:42, 11 March 2025

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=== Document type declaration ===

HTML documents are required to start with a d[[Document type declaration|ocumentdocument type declaration]] (informally, a "doctype"). In browsers, the doctype helps to define the rendering mode—particularly whether to use [[quirks mode]].

The original purpose of the doctype was to enable the parsing and validation of HTML documents by SGML tools based on the [[document type definition]] (DTD). The DTD to which the DOCTYPE refers contains a machine-readable grammar specifying the permitted and prohibited content for a document conforming to such a DTD. Browsers, on the other hand, do not implement HTML as an application of SGML and as consequence do not read the DTD.

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* Use the empty-element syntax only for elements specified as empty in HTML.

* Remove the closing slash in empty-element tags: for example {{code|lang=html|code=<br>}} instead of {{code|lang=html|code=<br/>}}.

* Include explicit close tags for elements that permit content but are left empty (for example, {{code|lang=html|code=<div></div>}}, not {{code|lang=html|code=<div />}}).

* Omit the XML declaration.