What are DOCTYPES? What are BROWSER QUIRKS & STRICT Mode?

Nikhil — Fri, 14 Sep 2007 22:49:34 +0000

Simple speaking (for those who never heard about doctype before today)! DOCTYPE is the declaration in a HTML document that comes before the tag, that looks something like this ( pasted from the source of this very page)

Why use doctype?
It all began when browser standards were introduced by W3C. The earlier web developers implemented CSS according to the wishes of browsers, to have the pages rendered correctly in them and most websites had CSS that didn’t quite match these specifications/standards.

Therefore solution to this problem was to

allow web developers who knew their standards to choose which mode to use.
continue displaying old pages according to the old (quirks) rules.

And DOCTYPE was born.

So, based on whether you page is designed to standards or not , you choose the appropriate doctype.

Relation between Doctype & Browser modes
Doctype is the statement that tells your browser what mode it should render the HTML page in or rather to be more precise how should the browser interpret the CSS in; Quirks Mode or Strict mode.

Old pages written before these standards were introduced don’t have a doctype. Therefore when there is no DOCTYPE in your HTML then the browser is in QUIRKS mode.
But if the DOCTYPE is defined as one of the following , then the browser is said to be in STRICT Mode.

Expressing IT » modes

What are DOCTYPES? What are BROWSER QUIRKS & STRICT Mode?