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2.  Keyword based: Keyword based search engine helps to search information when related words for
                    required  information are typed.  The  engine  displays a  list of web pages that  contain  information
                    related to the typed  words. It is more useful for  searching about  topics that  do not occur  under
                    general subjects or categories.
                    When a user submits a few words related to the information to the search engine, it starts searching
                    for that information to match the web pages related to the user’s information and then displays the
                    list of the locations that match the search criteria. These types of search engines are also called index
                    based search engine. For example: www.google.com, www.bing.com, www.altavista.com, etc.


                 How does a Search Engine Work?
                 A Search Engine works in the following ways:
                   A search engine must have a very strong database for which the search engines use powerful programs
                    called ‘Spider’ or ‘Web Crawler’ that keep on crawling on the web to catch any newly published web
                    page or document and find their web address.
                   The documents and their web addresses are sent to the indexing tool which stores it in a database. It
                    also prepares an Index so that the information can be retrieved quickly from the database.
                   When the user enters the keywords or a query, the search engine weeds through millions of web pages
                    and the search software searches its database with the help of an index and displays the matching
                    documents or links.
                 Search engines display the related information in a hierarchical order, instead of being listed by how
                 relevant the search engine thinks the site to search. On the other hand, guides or indexes contain links
                 to many important resources on a topic. They search the contents of websites. The indexes usually
                 rank the search results in order of relevance in accordance with how closely the document matches the
                 content that is searched for.

                      Do you know?

                      Presently, there are more than 1.7 billion web pages on the Internet and this number is increasing day
                      by day. Incidentally, even the most powerful search engines cover only a small percentage of the web!



                 Suggested Tips for Using a Search Engine
                 To make an effective search on the Internet for a specified information:
                   Be specific, use synonyms and use lower case letters.
                   Avoid using common words, like ‘Internet’, ‘Computer’, etc., as these words are too general, hence the
                    search engine will display thousands of matching web pages.

                   Many search engines can search for information with a combination of multiple words. By using the
                    Boolean Operators (AND/OR/NOT) in queries, the result of searching can be better.
                   To search information on the basis of words or a phrase or a title, enclose them within quotes. For
                    example, to find a book named ‘The ABC of the Internet’, type “The ABC of the Internet” in the search
                    box of the search engine.

                   Use wild cards like asterisk (*) to search for related words without entering the full word. For example,
                    if we type ‘*comput*’, then the search will include computer, computers, computing and other related
                    words starting with the letter ‘comput’.


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