Search Tips

Boolean AND, OR and NOT | Truncation and Wildcards | Phrase Searching

Putting Concepts Together - Boolean AND, OR and NOT

Web search engines like Google assume you want to search all terms you type in. Other web search engines rank by relevance - results with all terms come up first, then results with only one term. Library databases have more sophisticated search capabilities and requirements; you must specify how the system should deal with multiple terms.

Use the operators AND, OR or NOT to combine keywords or phrases.

  • AND narrows a search - results must contain both terms.
    Use AND to combine separate concepts.
  • OR broadens a search - results can contain either term, or both.
    Use OR to combine synonyms.
  • NOT narrows a search - results can contain one term, not the other.
    Use NOT to exclude terms
Operator Sample Search The search will find... Diagram of Results
AND careers
Items that contain both
"careers" and "medicine"
Venn diagram for Boolean AND
OR occupations
Items that contain either
"occupations" or "careers"
Venn diagram for Boolean OR
assisted suicide
Items that contain
"assisted suicide" but not "kevorkian"
Venn diagram for Boolean NOT

Truncation and Wildcards

A symbol at the end of a word stem provides for all variants on the word stem. The most commonly used symbol is the asterisk (*), but this varies among databases.

For example, a search for


will retrieve:

library, libraries, librarian, etc.

Be careful not to truncate too far, or you will retrieve unrelated words!

Internal Truncation

A symbol within a word provides for all possible variants inside a word or word stem. The most commonly used symbol for internal truncation is #. For example, a search for


will retrieve:

woman, women

Look at online help for each database to determine the truncation symbols.

Phrase Searching

Some databases require a phrase to be in quotes.  Ex: "higher education"

Content based on Duke University Guide to Library Research: Electronic Searching