When a visitor performs a search on AltaVista, a program sifts through millions of pages recorded in its index to find matches to the search and then ranks the results in order of what it believes is most relevant. Directories, such as Yahoo, depend on humans for their listings. Editors manually review each Website and then determine placement within the directory listing. Techniques that are useful for improving a listing within a search engine have no effect on improving a listing within a directory. The only exception is that a good site, with good content, might be more likely to get reviewed than a poor site.
Most people mistakenly think that search engines actually search the Web.
What search engines really do is search their internal database of registered Websites. Only those Websites that have registered with a particular search engine have any chance of showing up in the results pages. This is why an identical search performed on two different search engines can have completely different results. So, if you want to be listed on a particular search engine, you have to go to that search engine and register. Continued Most people are familiar with META tags, those special keywords you insert within the code of your Website to spoon-feed search engines all the search words you want associated with your Website.