Yahoo! is a directory that also integrates search engine results into its returns. This makes it a category all unto itself. Through an alliance with first Alta Vista and then with Hotbot and now with Google, when a surfer makes a search request, if no listing is found within Yahoo! then the search is automatically and transparently defaulted to the larger, spider-generated database. So you may think your website has a Yahoo! listing when you see your site in a Yahoo! results page, but that listing may have been generated from the search engine’s larger database. This isn’t the same as a true Yahoo! listing.
It is very difficult to get a good listing on Yahoo!, but it is well worth the effort since the site, as a whole, is the most popular site on the Web. Yahoo can generate much of your site’s traffic — if you can obtain a successful listing.