Chapter 7 helped you create the best navigation system possible for your web site. This chapter describes another form of finding information: searching. Searching (and more broadly, information retrieval) is an expansive, challenging, and well-established field, and we can only scratch the surface here. We'll limit our discussion to what makes up a search system, when to implement search systems, and some practical advice on how to design a search interface and display search results.
This chapter often uses examples of search systems from sites that allow you to search the entire Web in addition to site-specific search engines. Although these web-wide tools tend to index a very broad collection of content, it's nonetheless extremely useful to study them. Of all search systems, none has undergone the testing, usage, and investment that web-wide search tools have, so why not benefit from their research? Many of these tools are available for use on local sites as well.