What is Search Engine?
A Web search engine is a tool designed for the convenience of people using internet to search for information on the World Wide Web. The search results usually come in a list and are commonly called hits. The information may consist of web pages, images, information and other types of files. Some search engines also extract data available in newsbooks, databases, or open directories.
On the Internet, a search engine is a coordinated set of programs that includes:
- A spider that goes to every page or representative pages on every Web site that needs to be searched and reads it, using hypertext links on each page to discover and read a site's other pages.
- A program that creates a huge index (sometimes called a "catalog") from the pages that have been read.
- A program that receives the search request, compares it to the entries in the index, and returns results to the searcher.
Google, Yahoo and MSN are the most widely-used directory on the Web as a search engine. A number of Web portal sites offer both the search engine and directory approaches to finding information. Major search engines such as Google, Yahoo, AltaVista, MSN and Lycos index the content of a large portion of the Web and provide results that can run for pages - and consequently engulf the user.
