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Gerald R. Sherratt Library


Information Literacy & Library Research: Keywords and Boolean Operators

Information literacy is the ability to know when information is needed and to be able to identify, locate and evaluate, and then legally and responsibly use and share that information.

Database Searching Logic

Unlike Google, which uses artificial intelligence to filter and refine your searches for you, guessing at what you mean and making mistakes, the databases used at the library are much more basic. They are fast and not fancy or smart. They use logic and keywords to search their vast collections to give you the results, and they will take whatever you enter into the search box literally.

This guide will give you more details on how databases use keywords and logic to create their searches.

Note for INFO 1010:

The module 3 assignment is all about database searching, and you will have to create several different database searches using keywords and Boolean operators. Having a clear understanding of what each operator does and how it affects the scope of your results will help you in your searching a lot. Pay close attention to how each operator affects your results and how to use the formats, such as parentheses and the different search boxes in Academic Search Ultimate.

Keywords and Boolean Operators


Library Databases are extremely literal. They are fast, but not smart. They will search exactly what you enter, no more or less. Rather than the natural language we are used to, where you would put your research question directly into the Google search bar, library databases use keywords and logic to search database content.

Keywords are essentially the main points of your topic or research question (like the three elements of population, variable, and effect). Once you have a simple but good question, you can easily pull your starting keywords from it.

Question: How can dogs improve the mental health of college students?

Main Points: How might dogs (the variable) influence the mental health (the effect) of college students (the population)?

Keywords: dogs AND "mental health" AND "college students"

*It is best to put quotes around multiple words to keep them together, so that the database knows they are one keyphrase instead of two separate keywords that mean something different when they are searched separately (mental and health are not the same things as "mental health" as a united concept. Likewise, searching animal AND rights might bring up anything that mentions animal and mentions rights, but searching "animal rights" links them together as a single multi-word phrase).

Boolean Logic and Operators

Boolean is a simple logic (think math with words) that tells the databases how to search the keywords using a series of operators, the most common being AND, OR, and NOT.


AND is the most used of the operators, and basically tells the database that all the results have to contain both keywords. 

Dogs AND "Mental Health"

AND will always narrow your search and give you less results.


OR is used if there are multiple ways to say the same thing, such as synonyms.

(Dogs OR Canines) AND "mental health"

Parentheses are used around OR terms to group keywords together (just like in the order of operations in math) so that the database only applies the OR to those keywords.

OR is basically a shortcut for doing multiple searches at the same time, and should only used for terms that are interchangeable, so it doesn't matter if only one is used.

Searching (Dogs OR Canines) and "Mental Health" is effectively searching at the same time:

(Dogs AND "Mental Health")


(Canines AND "Mental Health")

Because it's combining multiple searches into one search, OR will broaden your search, giving you more results, because it catches all the articles that include one or more of the suggested keywords in the OR search statement. Remember that you still need to use parentheses for OR statements even if you use the stacked search boxes in Academic Search Ultimate. See below for two examples of how the same OR search might look in Academic Search Ultimate.

Academic Search Ultimate advanced search using the search (dogs OR canines) AND "mental health" in one box.

Academic Search Ultimate advanced search using the search (dogs OR canines) in the first box and "mental health" in the next box with the built in Boolean AND operator.



NOT is use when you want to exclude a keyword from your results, such as in the case of homonyms, or when the same spelling of a word means different things. Such as when you are researching about mental stress, but your results keep talking about broken bones, or stress fractures. 

Stress NOT Fracture

NOT will narrow your search because it will eliminate any results that contain the keyword after it.

Three venn diagrams showing the results of the three Boolean Operators AND, OR, and NOT.