Is DOCTYPE important for SEO?

[AdeLewis]

Hello fellow Mozzers.

I am just having a brief look at a potential clients website before speaking to them tomorrow and whilst looking at the source I noticed that they don't appear to have a clear definition for their Doctype.

All the have at the top of each page is

I have to admit that Doctypes aren't my strong point but I know that they are normally slightly more descriptive than this.

Can this have any effect on rankings? or is this just an issue for W3C validation?

Thanks

[SL_SEM]

If it is an HTML 5 page that should be just fine as it is the HTML 5 doctype tag.

Check out the info here: http://www.w3schools.com/html5/tag_doctype.asp

It might cause trouble with really old browsers, but if they have that going I would hope they have already thought about the reasons for and against using it

EDIT: even better link: http://www.w3.org/TR/html5-diff/#doctype