Boolean OperatorsBoolean operators connect your search words together to either narrow or broaden your set of results.
The two basic boolean operators are: AND and OR.
Use AND in a search to:
- narrow your results
- tell the database that ALL search terms must be present in the resulting records
The triangle in the middle of the Venn diagram below represents the result set for this search. It is a small set using AND, the combination of all three search words.
Example: prison AND women AND California 
Use OR in a search to:
- connect two or more similar concepts (synonyms)
- broaden your results, telling the database that ANY of your search terms can be present in the resulting records.
All three circles represent the result set for this search. It is a big set because any of those words are valid using the OR operator.
Example: prison OR incarcerated OR crime 
Phrases
Most databases allow you to specify that adjacent words be searched as phrases. Using quotes around search words is a common way to do phrase searching, but not all databases or search engines use them. Example:"prison industrial complex"
Truncation
Truncation is a technique that broadens your search to include various word endings and spellings. To use truncation, enter the root of a word and put the truncation symbol at the end. The database will return results that include any ending of that root word.
Examples:
child*= child, child's, children, children's, childhood
educat*= educate, educated, educating, education, educational.
Truncation symbols may vary by database; common symbols include: *, !.
Keyword vs. Subject
Subject headings (a.k.a. descriptors) describe the content of each item in a database. Use these headings to find relevant items on the same topic. Searching by subject headings is the most precise way to search article databases. It is not easy to guess which subject headings are used in a given database. For example, the phone book's Yellow Pages use subject headings. If you look for "Movie Theatres" you will find nothing, as they are listed under the subject heading "Theatres - Movies." Keyword searching is how you typically search web search engines. Think of important words or phrases and type them in to get results. Here are some key points about each type of search:
To find subject headings or descriptors for your topic:
- Start with a keyword search, using words/phrases that describe your topic or that you think authors would use.
- Browse the results; choose 2 or 3 that are relevant.
- Look at the Subject or Descriptor field and note the terms used (write them down or click on them if they're links).
- Redo your search using those terms. Your results will usually be more precise than your initial keyword search.