LibGuides: Search Help: Common Search Problems: I don't understand AND, OR and NOT

AND, OR and NOT will make your searches great

Tired of reading? scroll to the bottom of this page to watch a video instead!

Before you're ready to enter your keywords into a search engine, take a moment to learn about the operators AND, OR, and NOT. These are sometimes called Boolean logic operators.

Don't worry! It's not as scary as it sounds. Boolean operators are used between two or more keywords to complete the phrase “I want records that contain _____”.

•AND – both terms are required to appear in a record.

Example: I want records about how secondhand smoke affects people with asthma, so I want records that contain secondhand smoke AND asthma

•OR – at least one term is required to appear in a record.

OR is useful to account for multiple synonyms, acronyms, word variations, plurals, and verb conjugates

Example 1: I want records about patient education, but there are many synonyms for the word education in this context. That means I want records that contain education OR counseling OR teaching OR motivational interviewing.

Example 2: I want records related to preeclampsia, but there is another way to spell this word: pre-eclampsia. Therefore, I want records that contain preeclampsia OR pre-eclampsia.

•NOT – the term following “NOT” must be absent from a record in order for it to be returned by the search

Example: I want records about the nursing profession, but I'm getting too many results about nursing mothers. To subtract those records from my results, I want records that contain nursing NOT mothers.

The quick way to remember this is that synonyms/related terms should be combined with OR. Different concepts should be separated with AND. For example:

Autism OR autistic OR ASD

AND

Young adult OR young adults OR adolescent or teenager or teenaged or “high school”

AND

Speech generation OR speech generating

AND

ASL OR sign language

Use the advanced search form of the database you choose to organize these strings and connect them with AND operators to make sure at least one word from each concept is found in every result returned by the search.

See how we're using the search boxes to combine each string together using the AND operator into one big search?

Practical tip: In your real search, don't combine too many concepts together. In reality, you should try 2 or 3 concepts to start, and then add concepts in to narrow your search further with each try. (Running the search shown above returns 0 results!)

Watch this video to learn about Boolean operators!