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VVC Library: Boolean Searching - Web & Databases

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Boolean Searching : Web and Databases

The key to being an effective online searcher is to use common search techniques that can be applied to most any Web search engine as well as online databases. The Boolean search techniques described below will enable you to quickly retrieve relevant information without having to sift through thousands of unrelated links.

What is Boolean Searching?

 Origin
Boolean searching was developed by the British mathematician George Boole in the 19th century. Simply described, it is a logical method of connecting search terms with AND, OR, and NOT (known as "Boolean Operators") to either narrow, expand, or exclude information in a search. Given the overwhelming amount of information available on the Web and in online databases, Boolean operators can help you focus a search, particularly when your topic contains multiple terms.


The AND Operator

Use AND in a search to:

  • Narrow search results
  • Indicate that ALL search terms must be present in the results
  • Example: college AND financial aid AND scholarships

Things to consider:

  • Always Capitalize Boolean operators (AND OR NOT)
  • In many search engines (Google, Yahoo, etc.) and databases, the default for a Space between words is the same a typing AND. Typing financial aid will retrieve Web sites that contain the term financial and the term aid but not necessarily in that order. It may also retrieve Web sites about foreign aid or financial crisis simply because one of the search terms is mentioned in the site.
  • In some search engines, the "+" symbol is used in place of AND (note that there is no space between + and the term: +cloning +humans +ethics).

The OR Operator

Use OR in a search to:

  • Connect two or more similar concepts (synonyms)
  • Broaden your results, indicating that ANY of the search terms can be present in the results.
  • Example: college OR university

Things to consider:

  • If you only search college you may miss Web sites or articles that use the term university in place of college.
  • Typing college university without OR is the same as typing college AND university, indicating that both terms must appear in the article, not either term.

The NOT Operator

Use NOT in a search to:

  • Exclude words from your search
  • Narrow your search by ignoring concepts that may be implied in your search terms.
  • Example: financial aid AND scholarships NOT student loans

Things to consider:

  • Other Examples: harry potter NOT movie; mustang NOT horse; apple NOT computer.
  • In some search engines (ex. Google), the "-" symbol is used in place of NOT (note that there is no space between - and the term: financial aid -loans).

Combining Boolean Operators

Use Quotation Marks " " in a search to:

  • Find an Exact Phrase.
  • Limit your search to include Web sites or articles that include the same words in the same order as what appears between the quotation marks.
  • Example: "financial aid" AND scholarships


Use Parentheses ( ) in a search to:

  • Combine or "Nest" sets of Boolean operators to control the order in which terms are searched when using two or more operators.
  • Examples: "financial aid" AND (college OR university) NOT "student loans"

Things to consider:

  • Searching with Boolean operators can vary from one search engine or database to another; + instead of AND, - instead of NOT, etc. Always check the search "Help" features to see what operators are supported.
 
Note: Most of the techniques described above are embedded in the "Advanced Search" features commonly found in search engines and online databases.