The exact mechanism is slightly different for each engine. These usually can help a little, but they don't guarantee a boost to the top. The information below describes some of the more common relevancy boosters listed on the chart. Reviewed Indicates whether being reviewed in a search engine's associated directory can give a site a relevancy boost. As above, all search engines can determine the popularity of a page by analyzing how many links there are to it from other pages.
Some engines give pages with lots of links, or links from important web sites, a relevancy boost.
Some search engines give pages an extra boost if search terms appear in meta keywords or description tags. Please note that those marked as No Boost may still support meta tags, as explained in the Meta Tag Support section below. It's just that these search engines don't attach any excess importance to terms appearing in meta tags. This is where a word is repeated many times in a row. If the search engines spot a spamming technique, they may downgrade a page's ranking or exclude it from listings altogether.