Boolean Searches

  • Boolean and Non-Boolean Searches

    One of the things that will make you a better web searcher is understanding what you need to type in order to tell the search engine exactly what you are looking for.

    There are two categories of search operators: Boolean and non-Boolean operators.

    An operator is a word or symbol that you type in that gives the search engine directions to help it know what to search for.

    Using these operators can narrow or widen your search, helping you find web sites that may be useful to you.

    You will have to check out the individual search engines to find out which operators work.

    Boolean Searching:

    See a visual example HERE

     

    AND

    AND means the search results must have both search terms


    AND finds fewer web sites, narrowing your search

    Example: pollution AND water

    will look for web sites about both pollution and water

    OR

    OR means the search results can have just one of the terms

    OR finds more web sites, broadening your search

    Example: pollution OR water

    will look for web sites that mention either pollution or water

    NOT

    NOT means any result containing the second term will be excluded

    NOT finds few web sites, narrowing your search.

    Example: pollution NOT water

    will look for web sites about pollution that do not involve water

    Warning: Be very careful about using NOT . If the web site mentions water even once, it may be left out of the web site list. This could rule out some very useful sites.

     

    Non-Boolean Searching:

     

    +

     

    + works like AND , making the term required in the search results
    the + should be placed directly in front of the search term without any spaces

    Example: pollution +water

    will look for web sites about pollution that also mention water.

    -

     

    -works like NOT and means to exclude the term
    the - should be placed directly in front of the search term without any spaces

    Example: pollution -water

    will also look for web sites about pollution that do not involve water.

    Warning: Just as with the Boolean terms, you must be careful when using- that you do not eliminate web sites that might mention the term you do not want, but are not really about that term. -water may eliminate web sites that are about air pollution but mention water pollution as well.

    ""

    " " placed around terms means the search engine will look for the exact phrase

    Example: " water pollution "

    will look for that exact phrase. This can make your search very specific.

     

     

    How to find out which search operators to use:

    Different web sites and search engines use different systems, and you will need to learn which search terms work best with your particular search engine.

    Many web sites and search engines will tell you which to use if you click on buttons such as HELP or ADVANCED SEARCH or POWER SEARCH or SEARCH TIPS. They may also offer other search limit options such as letting you pick dates or languages. Explore your favorite search engines to find out what they can do!

    Want to know more about searching online?

    Click on the link below to find out more about how to tailor your terms to focus your search.
    Advanced Search Engine Tips

    Or, here are some useful sites that will give you even more information about using search engines.

    The Nueva School page at http://nuevaschool.org/~debbie/library/research/adviceengine.html gives you information about which search engines are best for different types of searches.

    Search Engine Watch is a site that has a great deal of information about different search engines and how they work.

    At the Search Engine Showdown web site you can find a list of search engines and the different searching features they offer. Or, if you would prefer, you can see the different features in a CHART . You can click on each term on the site to find out more about what it means or read reviews of the different search engines.