Google Defines Semantic Closeness as a Ranking Signal, by Bill Slawski, SEO by the SEA (May 12)
Google filed a patent back in 2004 on using page structure to assist in semantic analysis of the page and ranking the search result – lists in particular. Google would be able to assess that keywords in a header are related to the list below and consider those words as “close”to items in the list when ranking search results.
“In other words, the search engine is attempting to locate and understand visual structures on a page that might be semantically meaningful, such as a list of items associated with a heading. We’re told that this process may also look for other kinds of meaningful semantic structures other than just lists as well.”