This document discusses search engines, including their definition, history, importance, and types. It describes how search engines work by using spiders to crawl the web and create searchable indexes. The main types of search engines are described as crawler-based (like Google and Yahoo), directories (like Yahoo Directory), hybrids (like Yahoo), and meta search engines. Search engines make the immense amount of online information accessible by filtering it into easy-to-use results. Proper use of search engine operators like quotes and Boolean operators can refine search results.