Definition: There are two main concepts behind Google Custom Search: first, to create a more user-friendly, efficient, and ultimately relevant search experience for searchers that visit self-hosted Web sites, and second, to give people the ability to create their own customized search engines that only search a pre-approved list of Web sites.
For example, if you own your own Web site, you can use Google Custom Search to offer visitors an easier way to search what you have to offer them. You get to choose which pages to include or not, plus, you can totally customize the Google Custom Search box to fit the look of your site.
Google Custom Search also gives anyone who wants to the chance to build their very own search engine; one that only searches specific Web sites. For instance, say you're really into model trains, and you'd like an easier, faster way to bring up information instead of just a general search engine query. A Google Custom Search engine would fill this need nicely.
