5.1 Introduction

Every day, all around the world, millions of people use search enginesA tool for searching the Internet. Users of search engines enter keywords relevant to their search, and the search engine returns results from its databases. to find content on the Internet. Search engines are Web-based programs that indexThe databases for keywords created by the search engines. the Web and allow people to find what they are looking for. “Search,” or “search marketing,” is often used to refer to the industry that has built up around search engines.