HTML <doctype> Tag
The HTML <doctype> tag is used for specifying which version of HTML the document is using. This is referred to as the document type declaration (DTD).
NOTE: The <!DOCTYPE> tag does not have an end tag!.
<!DOCTYPE html> <html> <head> <title>HTML doctype Tag</title> </head> <body> <p>doctype declaration <doctype> is mentioned at the starting of every HTML document.</p> </body> </html>
This will produce following result:
doctype declaration <doctype> is mentioned at the starting of every HTML document.
HTML 4.01 has 3 possible doctypes: HTML 4 Strict, HTML 4 Transitional, and HTML 4 Frameset. Every HTML document you create should have one of these three DTDs.
HTML 4 Strict
This document type includes all HTML elements except those that have been deprecated, and those that appear in frameset documents.
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "https://www.w3.org/TR/html4/strict.dtd">
HTML 4 Transitional
This document type includes all HTML elements including those that have been deprecated.
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "https://www.w3.org/TR/html4/loose.dtd">;
HTML 4 Frameset
This document type includes all HTML elements in the transitional DTD as well as those in framed document.
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN" "https://www.w3.org/TR/html4/frameset.dtd">
HTML 5 Declaration
In HTML5 there is only one declaration i.e.