Boolean Operators: AND, OR, & NOT

Boolean Operators are words that can be used to limit or expand searches in almost any electronic database-including the Web, Library Databases, and the Library Catalog

AND

OR

NOT
And limits your search. The database or catalog will find entries that contain both of the search terms.

OR expands your search to find entries that contain either word or phrase.

NOT acts as a limiting agent in searches. It will exclude the second term from any searches containing the first term.

AND: Children and Violence

OR: Copts or
Coptic

NOT: Chinook not Salmon

For Example: children and violence. The search finds only the records that contain both children and violence. The Venn Diagram above the area of overlap is what was retrieved in the search "children and violence"
For Example: Copts or Coptic. The search will find all the records that contain either the term Copts or Coptic. In the Venn Diagram above, the highlighted area shows what was retrieved in the search "Copts or Coptic"
For Example: Chinook not Salmon. The seach Chinook not salmon will retrieve records that contain the term Chinook, without the term salmon in the record. In the Venn Diagram above, the highlighted area shows what your search for chinook not salmon would retrieve.

 

Hints for Successful Boolean Searching

  1. Using the operators AND/NOT will always narrow your search, increase the specificity of your search, and limit the number of entries retrieved.
  2. The Boolean operator OR will always broaden your search and increase the number of entries retrieved.
  3. Before you begin your search, think about the terms you want to use. Select key ideas and write as many synonyms for those. Depending on the initial results of your search use the Boolean operators to increase or limit your search.
  4. Experiment with different search terms and Boolean operators to see what gets the best results.