ABSTRACT
This chapter considers one of the most widely used Internet services, Internet search. It considers the broad question of how a search company catalogs the information on millions of web pages that change constantly, and how such a site can answer queries quickly. A database provides an example of one way that information can be organized to make searching easy. The information in a database is structured because each record in the database has the same fields, and each field has a specific meaning; the meaning is set when the database is created. The task of classifying all information on the Internet is overwhelming for two reasons. First, the Internet contains vast amounts of information. Second, new types of information appear continuously. Internet search is among the most popular services available. To achieve accurate results, a search engine uses indexing in which a set of keywords are extracted from a page that distinguish the page from others.
