In the front of the book is a table of contents. In the back, an index.
Search engines are like indexes of a book.
Search engines, like the ones located on the web portals such as Yahoo, AttaVista, HotBot, Lycos, Deja News etc. Then, you scan these results, click on a link that sounds interesting, and you should be on your way to that page. Some web portals also act like the table of contents of a book even though they feature a search engine prominently at the top of the page. Here, they also feature several general categories of links below the engine, thus resembling a table of contents. When you click on these categories, they usually take you to another page which lists several pages or sites of interest for you to pick from without having to use keywords or search engines.