Tech Tips
by Doug Lamb
Search Engines
Did you ever wonder why, when you type the same query in two different search engines on the Internet, you often get two completely different lists of topics? This month, I'll explain search engines a little more in-depth.
Search engines do not search the entire Internet each time they receive a query. This would take forever. Instead, the search engine keeps a list, called a catalog or index, of all the Web pages it knows. This catalog is rapidly checked to locate relevant pages containing that phrase, and the list of sites is displayed on your browser.
Search engines come in three types: active, passive and meta-search; each builds its catalog in a different way. Active search engines, such as AltaVista, Excite, HotBot, InfoSeek, Lycos, and WebCrawler, build their own catalogs, using programs called spiders. Spiders visit Web pages, explore all their links, and make notes about them in the catalog. If you build a web page and never tell anybody about it, an active search engine will never find it unless someone else has created a link to your site on another page.
Passive search engines, such as Yahoo, don't have spiders. Instead, they let people add to the catalog by registering their web pages. If your page is not registered on a passive search engine, that engine will not be able to list it.
A third type of search engine, called a meta-search engine, does not have its own catalog; it borrows the catalogs of other engines. When you give it a query, the meta-search engine forwards your query to other search engines, collects the results, and presents them to you, all automatically. Internet Sleuth, MetaCrawler, Net Locator, SavvySearch, and Startin Point are all examples of meta-search engines. In other words, meta-search engines search both active and passive engines to find your query.
If you're looking for up-to-date information, active catalogs tend to be the most useful, since their spiders are constantly locating new pages. Passive engines tend to have fewer items, but are often indexed better. Passive sites are useful for locating general resources or the main page of a website. Meta-search engines require that your query be precise, since they access so much data but only display the first 10-20 sites found.
Click on the "Search" icon in either Netscape (http://home.netscape.com/home/internet-search.html) or Internet Explorer (http://home.microsoft.com/access/allinone.asp) and you'll find an all-in-one page with access to most of the active, passive, and meta-search engines I've mentioned above. With a little planning and practice, you'll be able to find the information you need in no time.
Doug Lamb is a PC technician at MIRAD Computers.