HTML Doctype

The doctype in HTML is something that has to be declared at the beginning of the document. This tells the browser which type of file it is parsing.

Versions
There are many ways to put a doctype in the file. The different versions of HTML have different ways of doing it.

HTML5
In HTML 5.0, this is how you put a doctype in the file.

In older versions, the doctype was more complicated.