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CRAWLING THE WEB

CRAWLING THE WEB. CRAWLING THE WEB. What do you do when you need information from the internet? . Search Engines. directories. Open directory project (DMOZ). Meta-search engines. FINDING INFORMATION ON THE WEB. SEARCH ENGINES DIRECTORIES META-SEARCH ENGINES.

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CRAWLING THE WEB

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  1. CRAWLING THE WEB

  2. CRAWLING THE WEB • What do you do when you need information from the internet?

  3. Search Engines

  4. directories Open directory project (DMOZ)

  5. Meta-search engines

  6. FINDING INFORMATION ON THE WEB SEARCH ENGINES DIRECTORIES META-SEARCH ENGINES

  7. How does a SEARCH ENGINE work? • Search engines use a computer program called a SPIDER to roam the World Wide Web pages and their links.

  8. How does a search Engine work? • The spider collects the information and then indexes all the information.

  9. HOW does a search Engine Work? • Each search engine’s spider indexes and organizes the Web pages • While indexing, matches between keywords and Web pages are found. The sites with the best matches are displayed first. Each search engine has a different way of identifying the best sites.

  10. How does a search engine work?

  11. How does a search engine work? • ROAMS and COLLECTS INFORMATION • INDEXES ALL THE INFORMATION • MATCHES THE INFORMATION These 3 tasks are all done WITHOUT ANY HUMAN INVOLVEMENT– so a huge number of sites are indexed quickly.

  12. How does a directory work? • In a DIRECTORY, PEOPLE, not computers, put the index together.

  13. How does a directory work? • Editors evaluate Web sites and organize them into subject categories. • Because people have chosen them, the sites in directories may be of higher QUALITY.

  14. How does a directory work? • The number of sites in a DIRECTORY is usually much SMALLER than in a search engine’s index. • Many people use the term “SEARCH ENGINE” to describe either a search engine or a directory. That is because many search sites offer both services.

  15. How does a meta-search engine work? • A META-SEARCH ENGINE sends your keywords to several search engines at the same time. • The results from each search engine are organized and displayed on one page.

  16. How does a meta-search engine work? • This type of service is useful when your topic is very NARROW and you want to search as many Web sites as possible.

  17. Remember … • No one search engine, directory or meta-search engine covers the entire Web. So, don’t get stuck in a rut by using only one. Try them all!

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