Before you optimize for the search engines, you should understand the basic search engine landscape. You can break the landscape into search sites, search systems, search engines, and search directories:

  • Search site: A search site is a website where you can search. Google’s a search site, AOL is a search site, and Yahoo! is a search site.

  • Search system: Many search sites get their data from other companies. Search systems are companies that create search data. For instance, Google is a search system that feeds data to AOL and many other sites.

  • Search engine: A search engine is a system that indexes individual pages inside websites.

  • Search directory: A search directory is a collection of information about particular websites. A search directory doesn’t index pages inside those sites; it just contains basic information about each site. is one of the oldest and most important search directories. Search directories are far less popular than they used to be. (Most people don’t even know they exist.)

The three most important search sites are Google, Yahoo!, and Bing. Google and Bing have their own search engines. However, Yahoo!’s search engine actually provides data from Bing; Yahoo! no longer maintains a search-engine index itself.

Google dwarfs all other search systems. Around 65 percent of regular search-engine searches are down at the Google search site. Add in the sites that Google feeds search results too (such as,,, and so on), and Google is responsible for about 67 percent of all searches.

Bing is responsible for around another 30 percent of searches, including the results it feeds to Yahoo!. is often included in the list of the top search engines; but it’s only responsible for a couple of percent.

Don’t forget, however, that not all searches occur at regular “search engines”; people often search for information at video sites, social-networking sites, online stores, and the like. For instance, billions of searches are carried out every month at,,,, and So if you sell products, focusing purely on the regular search engines is a big mistake; most “product” searches are carried out elsewhere.