Search Engine Optimization-Keyword Search
Tuesday, July 15th, 2008Most search engines handle words and simple phrases. In its simplest form, text search looks for pages with lots of occurrences of each of the words in a query, stopwords aside. The more common a word is on a page, compared with its frequency in the overall language, the more likely that page will appear among the search results. Hitting all the words in a query is a lot better than missing some.
Search engines also make some efforts to “understand” what is meant by the query words. For example, most search engines now offer optional spelling correction. And increasingly they search not just on the words and phrases actually entered, but the also use stemming to search for alternate forms of the words (e.g., speak, speaker, speaking, spoke). Teoma-based engines are also offering refinement by category, ala the now-defunct Northern Light. However, Excite-like concept search has otherwise not made a comeback yet, since the concept categories are too unstable.
When ranking results, search engines give special weight to keywords that appear:
* High up on the page
* In headings
* In BOLDFACE (at least in Inktomi)
* In the URL
* In the title (important)
* In the description
* In the ALT tags for graphics.
* In the generic keywords metatags (only for Inktomi, and only a little bit even for them)
* In the link text for inbound links.
More weight is put on the factors that the site owner would find it awkward to fake, such as inbound link text, page title (which shows up on the SERP — Search Engine Results Page), and description.