Search Engines


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Search engine basics and types

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  • Search Engines

    1. 1. Search Engines Shamprasad Pujar IGIDR, Mumbai [email_address]
    2. 2. Agenda <ul><li>Basics of Internet </li></ul><ul><li>Basics of Search engine </li></ul><ul><li>What is a search engine? </li></ul><ul><li>Functioning of a search engine </li></ul><ul><li>Methods of indexing or searching </li></ul><ul><li>Types of Search engines? </li></ul><ul><li>Advantages of Search engines? </li></ul><ul><li>Disadvantages of Search engines? </li></ul><ul><li>Search engines v/s Directories v/s portals </li></ul><ul><li>Limitations of search engines </li></ul><ul><li>Q & A </li></ul>
    3. 3. Basics of Internet <ul><li>Anybody can publish anything on the net </li></ul><ul><li>Content and features of sites change very fast </li></ul><ul><li>No bibliographic control on published information </li></ul><ul><li>Internet is a self publishing tool-Evaluate </li></ul><ul><li>Try out multiple sites, while looking for information </li></ul><ul><li>Subject Directories and Search Engines vary in their contents </li></ul><ul><li>Subject Directories/Search engines are highly volatile </li></ul><ul><li>Good source to locate scholarly literature </li></ul>
    4. 4. Basics of Search Engines <ul><li>Store millions of pages in their databases </li></ul><ul><li>Sites are included automatically based on a set criteria. No human interference </li></ul><ul><li>Search features/scope vary greatly from one to another </li></ul><ul><li>Good for beginners and experts </li></ul><ul><li>Good for searching on a narrow topic </li></ul><ul><li>Search for particular types of documents, file types, etc is possible </li></ul><ul><li>Search for any kind of information is possible </li></ul><ul><li>Different search facility is available for sites, images, news, audio/video files, maps etc </li></ul>
    5. 5. What is a Search Engine? <ul><li>Search engine is a tool, which helps in retrieving </li></ul><ul><li>information from the Internet </li></ul><ul><li>It indexes the web and accordingly builds its databases </li></ul><ul><li>Each search engine has its own set rules to index </li></ul><ul><li>websites </li></ul><ul><li>When the query or keyword is entered in the search </li></ul><ul><li>box it checks its ‘index’ with the query </li></ul><ul><li>Relevant matches are retrieved and returned as 'hits' or </li></ul><ul><li>'search results‘ </li></ul>
    6. 6. Functioning of Search Engine?
    7. 7. Methods of Indexing and Searching <ul><li>Keywords from meta tags or web pages </li></ul><ul><li>Boolean (and, or, not) </li></ul><ul><li>Mathematical symbols (+, * -) </li></ul><ul><li>Concept /Computational </li></ul><ul><li>Natural language searching </li></ul>
    8. 8. Types of Search Engines <ul><li>General </li></ul><ul><ul><ul><li>Example: Bing, Google, Gigablast, etc </li></ul></ul></ul><ul><li>Meta Search Engines </li></ul><ul><li>Example: Dogpile, etc </li></ul><ul><li>Subject Specific search engine </li></ul><ul><li>Example: Scirus, Intute, Entrez, GoPubMed </li></ul><ul><li>Intelligent/Specialized Search Engines </li></ul><ul><li>Example: Kosmix, WolframAlpha </li></ul><ul><li>Deep Web/Invisible web </li></ul><ul><li>Example: Library catalogues, Databases </li></ul><ul><li>Scholarly literature </li></ul><ul><li>Example: Google Scholar, Base, OAISTER, etc </li></ul>
    9. 9. Types of Search Engines <ul><li>General Search Engines : </li></ul><ul><li>Have own database/index </li></ul><ul><li>Index sites using their software robot/crawler </li></ul><ul><li>Index sites on their policy </li></ul><ul><li>Rank web pages based on their policy </li></ul><ul><li>Meta Search Engines </li></ul><ul><li> Search different general search engines </li></ul><ul><li>Components </li></ul><ul><li>Dispatch mechanism  Interface Agents  Display </li></ul>
    10. 10. Types of Search Engines <ul><li>Subject Specific Search Engines: </li></ul><ul><li>Index sites on particular subject or material </li></ul><ul><li>Intelligent/Specialized Search Engines: </li></ul><ul><li>Concept based searching </li></ul><ul><li>Allow natural language searching </li></ul><ul><li>Use thesaurus </li></ul><ul><li>Personalized Services </li></ul><ul><li>Deepweb or Inivisible Web: </li></ul><ul><li>Search content stored in searchable databases </li></ul><ul><li>Scholarly Literature Search Engines </li></ul><ul><li>Search content from scholarly journals publishers websites/grey literature published from institutes and repositories </li></ul>
    11. 11. Advantages of Search Engines <ul><li>Enable to quick search to vast amount of information from one search box </li></ul><ul><li>Search on a specific type or piece of </li></ul><ul><li>information is possible </li></ul><ul><li>Different types of search engines enable to look for specific types of documents </li></ul>
    12. 12. Disadvantages of Search Engines <ul><li>Creates information overload </li></ul><ul><li>Semantic search is not possible </li></ul><ul><li>Privacy and security is of concern </li></ul><ul><li>Makes everyone to dependent </li></ul>
    13. 13. Search Engines v/s Directories v/s Portals <ul><li>SEARCH ENGINES </li></ul><ul><li>Crawl Web for information </li></ul><ul><li>Automatic Indexing </li></ul><ul><li>Change in webpage automatically gets updated </li></ul><ul><li>DIRECTORIES </li></ul><ul><li>Human editing </li></ul><ul><li>Change in webpage will not automatically updated </li></ul><ul><li>PORTALS </li></ul><ul><li>Information put by individuals or organizations </li></ul>
    14. 14. Limitations of Search Engines <ul><li>Can not index the entire web. Most of the search engines can index only between 40% and 60% of the web </li></ul><ul><li>Can not index sites governed by passwords and developed using frames </li></ul>
    15. 16. Q & A <ul><li>Questions and Answers ?? </li></ul>