It is used to search information on the internet for which special websites are made available known as search engines. A search maintains a database of keywords. When you request the search engine for information, it attempts to locate the specified information in its database of keywords. If the search engine finds a match it displays these references.
Accessing a search engine is just like accessing a website. For example, you can use thehttp://www.yahoo.com URL to reach the yahoo search engine. The available information is grouped under various categories.