As long as there's been a Web, there's been a need for search engines. Because of the volume of information that's available out there, people will always need help finding what they want. Nowadays, it's commonplace for individual sites, even personal homepages, to have their own search capabilities, and so a slew of new services have appeared to help you quickly and easily add search to your site. Some of the most popular include Atomz, FreeFind, intraSearch, MondoSearch, PicoSearch, SearchButton, SiteMiner, and Webinator.
Why would you want your own search engine? Because a Web site is not a book. Indexes in books are limited to what the author thought you might want to look for and to the context of their time. For example, if you're looking for information about the first cases of AIDS, you wouldn't be able to find that term in a book written in 1978.
Online search indexes, however, are automatic, complete, and change as the data changes. They match the fluid nature of hypertext. When you search a site for a particular word and get a bunch of results, then you know that the site will cover your topic. While search engines aren't perfect, they are like using a paint sprayer instead of a small brush: You get more coverage more quickly (though you have to be careful about the edges).
Some types of sites probably don't need their own search engines. Online exhibitions of art, animation, and video, for example, don't often have enough useful text to be searchable. Very small sites can been seen in their entirety in 10 or 20 clicks, and catalogs and other database-driven sites should use the database's search tool rather than a site search tool.
Nevertheless, the vast majority of sites out there could benefit from search capabilities, and it's amazingly easy to get set up. But first, let's take a look at how to prepare your site for search and what features you might need.