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Use parentheses ( ) to keep combination searches in order. In the example below, the database or search engine will retrieve articles or web pages that must contain the word law and at least one of the words in parentheses:
Boolean searching is based on a system developed by George Boole, a 19th century mathematician. Most library databases support Boolean searching and most Internet search engines support Boolean searching through their advanced search option. The power of Boolean searching is based on connecting keywords with boolean operators. The three basic operators are AND, OR and NOT. Here is how they work:
AND
Type AND between your keywords to narrow your search. The database or search engine will only retrieve those articles or web pages that contain both words. Using AND will decrease the number or hits or articles or web pages in your result list.
OR
Type OR between your keywords to broaden your search. The database or search engine will retrieve those articles or web pages that contain at least one of these words. Using OR will increase the number of articles or web pages in your result list (especially if not used in combination with AND or NOT). Use OR between keywords that are synonyms or have similar meanings.
NOT
Type NOT before a keyword to exclude that keyword from your search. Using NOT will also narrow your search. Using NOT will decrease the number of articles or web pages in your result list. Be careful when deciding whether you should use NOT in your search. The best use of NOT is when you are searching for a keyword that may have multiple meanings.