WHAT IS A SEARCH ENGINE?
The term web search is, for many of us, synonymous with Google - if you're looking to quickly and easily find something online. But there are hundreds of search tools available that might be better suited to the job at hand. Whether you are looking to track down a particular RSS feed, a photograph, or a local business, there are search "engines" out there waiting to lend you help you.

Internet search engines (ex. Google, AltaVista, Excite) are programs that create a directory of internet content.  If you're looking for specific information on the world wide web, a search engine will list web sites where you can find that information. 

HOW DOES IT WORK?
Typically, a search engine works by maintaining a database of web sites and use programs (often referred to as "spiders" or "robots") to collect information from as many documents as possible.  Another program, called an indexer, then reads these documents and creates an index based on the words contained in each document. Similar services are provided by "directories", which maintain ordered lists of websites, (ex. Yahoo!)

Each search engine uses a proprietary algorithm to create its indices such that, ideally, only meaningful results are returned for each query.