Search engines are among the most popular and most useful tools that the web has to offer. The vast amount of information that can be found on the internet can be accessed by using popular search engines such as: Yahoo!, Altavista, Hotbot, Excite, Lycos, Google, and many more. The importance of search engines can easily be seen since it's the place on the internet we all visit to find information on just about any topic.
             When it comes to search engines there are three types: crawler-based, human-powered, and hybrid (a mix of crawler-based and human-powered). Crawler-based engines are among the most popular. They work using software "robots" called spiders or crawlers. The purpose of these crawlers is to sift through web pages and follow links within websites. The crawler revisits the page from time to time to check for any changes that may have been made. The information found by the spider is then placed into the index. The index (sometimes referred to as the catalog) stores all the information like a library. The search engine then uses specific software to sort through the index to find the most useful and relevant matches according to your query.
             The second type of search engine, human-powered, is based on people submitting a short summary of a site which is then used to find matches, again, based on your query. The summary of the site can be written by the author or an outside editor. The last form of search engines is the hybrid engines which combine both crawler-based and human powered engines. With companies always trying to improve, hybrid engines have become a lot more common.
             Now you might wonder if all search engines fit under these three categories, why is that different engines produce different results. One cause is that the indexes of the engines differ. This means that the spiders used by different engines use different techniques in searching through sites. Some crawlers search through the w...