Question

what is called search engine

Answer 1

a program that searches for and identifies items in a database that correspond to keywords or characters specified by the user, used especially for finding particular sites on the World Wide Web.

Answer 2

A search engine is an information retrieval system designed to help find information stored on a computer system. The search results are usually presented in a list and are commonly called hits.

On the Internet, a search engine is a coordinated set of programs that includes:

1. A spider (also called a "crawler" or a "bot") that goes to every page or representative pages on every Web site that wants to be searchable and reads it, using hypertext links on each page to discover and read a site's other pages
2. A program that creates a huge index (sometimes called a "catalog") from the pages that have been read
3. A program that receives your search request, compares it to the entries in the index, and returns results to you
4. An alternative to using a search engine is to explore a structured directory of topics. Yahoo, which also lets you use its search engine, is the most widely-used directory on the Web. A number of Web portal sites offer both the search engine and directory approaches to finding information.

some Search Engine Approaches

• Major search engines such as Google, Yahoo (which uses Google), AltaVista, and Lycos index the content of a large portion of the Web and provide results that can run for pages - and consequently overwhelm the user.

• Specialized content search engines are selective about what part of the Web is crawled and indexed.