Document Type Declaration
The first thing any HTML document should have is a type declaration. This declaration tells the browser which version of the HTML/XHTML standards your document is going to use. Without such a declaration your HTML is not valid and the browser may interpret it freely.
Now, let’s take a look at what the declarations would look like for the various standards.
The document declaration for XHTML 1.0 Strict is shown below. This is what we suggest using.
1 2 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> |
The document declaration for XHTML 1.1 is shown below. This is the newest version of the standards but it requires to be served with a MIME type application/xhtml+xml which not all browsers understand.
1 2 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> |
The document declaration for XHTML 1.0 Transitional is shown below. This version is a bit more lax and closer to HTML 4.
1 2 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> |
For those of you that wish to use frames, the document declaration for XHTML 1.0 Frameset is:
1 2 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Frameset//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd"> |