A directive, found at the top of an HTML document, that indicate the document type used in the markup of the document itself. A DTD (Document Type Definition) describes the markup that can be used in a document that uses the DTD. The DOCTYPE is used when validating a document, and is used by some browsers to determine which rendering mode to use in the display of the document (see DOCTYPE switching).
a declaration that works as a top-level tag-like reference known as a Public Identifier
a Document Type definition, which tells the browser what version of HTML you have coded the page in
a means of specifying what syntax a web page uses
a statement that should be included at the top of your documents identifying which DTD you are using
a tag on first line of your site file telling the browser what markup language you will be using
A DOCTYPE (document type) definition, known as a DTD should begin an HTML document. This declares what type of page it is and what language is being used, and it allows the page to be validated as conforming to Worldwide Web Consortium (W563C) standards.
The keyword you enter on the command line to specify the type of document you want to create; for example, a letter, a software manual or an article. A doctype can have several different designs contained within it; if so, you specify a design as a keyword following the doctype keyword and separate it from the doctype keyword by a period (.).
The term used as the tag name designating the DTD or its reference within an XML document. For example, !DOCTYPE person SYSTEM "person.dtd" declares the root element name as person and an external DTD as person.dtd in the file system. Internal DTDs are declared within the DOCTYPE declaration.
The doctype or !DOCTYPE tag tells the browser what version of HTML or XHTML is used to design the page so it knows how to read and display the page.
A declaration at the start of an XML document that identifies the document's root element and DTD.
Let's browsers know what to expect and tells validators how to judge your code in order to check its syntax. Web Design
Document type Declaration - see appendix 3
The doctype of a webpage indicates what version of HTML (or equivalent) the browser should use to interpret the document.