Learn Html

HTML Doctypes

HTML doctypes

A doctype declaration refers to the rules for the markup language, so that the browsers render the content correctly.

Example
An HTML document with a doctype of HTML 4.01 Transitional:

<!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.01 Transitional//EN” “http://www.w3.org/TR/html4/loose.dtd“>
<html>
<head>

<title>Title of the document</title>
</head>
<body>
The content of the document……
</body>

</html>

HTML Different Doctypes

The doctype declaration is not an HTML tag; it is an instruction to the web browser about what version of the markup language the page is written in.

The doctype declaration refers to a Document Type Definition (DTD). The DTD specifies the rules for the markup language, so that the browsers render the content correctly.

The doctype declaration should be the very first thing in an HTML document, before the <html> tag.

Tip: Always add a doctype to your pages. This helps the browsers to render the page correctly!

HTML 4.01 Strict

This DTD contains all HTML elements and attributes, but does NOT INCLUDE presentational or deprecated elements (like font and center). Framesets are not allowed:

<!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.01//EN”
http://www.w3.org/TR/html4/strict.dtd“>

HTML 4.01 Transitional

This DTD contains all HTML elements and attributes, INCLUDING presentational and deprecated elements (like font). Framesets are not allowed:

<!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.01 Transitional//EN”
http://www.w3.org/TR/html4/loose.dtd“>

HTML 4.01 Frameset

This DTD is equal to HTML 4.01 Transitional, but allows the use of frameset content:

<!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.01 Frameset//EN”
http://www.w3.org/TR/html4/frameset.dtd“>

Tips and Notes:

Use W3C’s Validator to check that you have written a valid HTML / XHTML document!

HTML DOCTYPE Element

Tag Description
<!DOCTYPE> Defines the document type. This declaration goes before the <html> start tag

Validation tools

You can use several tools to validate your documents. Tools you have at your disposal include the following:

✦ The online W3C HTML validation tool, found at http://validator.w3.org/.

✦ Validation utilities built in to Web development tools such as Adobe’sDreamweaver.