There is an interesting Google Groups thread discussing how Google handles the <base> HTML tag. The base tag specifies a base URL for all the links in a page. But how does Googlebot or Google handle indexing this tag?

Google Groups member, Webado said you should be “careful using the base tag”. Why?

Member, RainboRick said that the major search engines typically “ignore the HTML mark-up in that regard (keyword density)- even MSN.”

Forum discussion at Google Groups.