Boolean searching allows the user to combine or limit words and phrases in an online search in order to retrieve relevant results. Using the Boolean terms: AND, OR, NOT, the searcher is able to define relationships among concepts.
Use OR to broaden search results. This expands the search to include all records containing either concept. Think of using OR in terms of synonyms or related terms; for example "challenges" OR "barriers" OR "weaknesses"; or in the illustration below endangered OR birds. However, this increases the possibility of reducing relevancy if you haven't selected the best keywords or concepts relationships.
Use AND to narrow search results. You're instructing the resource to retrieve only those documents or records containing both words or phrases; for example "online programs" AND "student success;" or in the illustration below endangered AND birds. The more terms added to the search, the narrower the results will be. Relevance of the retrieved items may depend upon the proximity of the words in the record (next to or near each other and in context).
Use NOT to narrow search results by eliminating specific words or phrases from the search results; for example student AND performance NOT musical will eliminate articles about student musical performances. While an effective strategy to reduce results, it may also eliminate documents with high relevancy to your topic.