Whenever you conduct a search in a search engine or
database, you typically type in whatever you’re
interested in—then the search engine or database gives
you the results of your search. This is how Google
works—it’s also how you search for books and articles
in library catalogs and library databases.
Boolean operators let you better control what sorts of
books or articles will appear in your search results.
Even more than this, Boolean operators are a helpful
way of conceptualizing your search. Once you’ve
learned how Boolean operators work, your search skills
will improve, whether that’s in a library database or
Understanding Boolean Operators and how
they work is useful for a couple of different
1. Boolean operators make it easier to find
the books and articles you need.
2. Boolean operators make your searches
more exact and thus more powerful. By
constructing more specific searches, you
narrow in on materials related to your
topic much faster.
So what are Boolean Operators? You’re probably
already using at least a couple of them. The
biggest three are:
Now let’s look at how to use them when you
“AND” lets you search for items that include two or more search terms or
keywords. Both terms must appear in the article or book in order for that
article or book to appear in your search results. Here are a few examples:
Try visualizing an “AND” search like this:
Searching just “Jim” will give you the first
circle of returns. Searching just “Jill”
would give you the second circle. But
searching “Jim AND Jill” will only give
you the shaded portion—ie, only the
results for where the two search terms
Jim AND Jill
dog AND cat
Olympics AND skiing
Poverty AND Crime
• Your search results will
show only items containing
both search terms.
• Blue shaded area
represents search results.
Here’s another example of using “AND”
“OR” lets you search two or more search terms at once. Unlike “AND”
searches, only one of the search terms need to appear in a book or article
in order for that book or article to appear in your search returns.
Try visualizing it like this:
Searching using “OR” gives you
EVERY article or book that
includes either of the two search
terms (or keywords). This sort of
search is great if you’re unsure of
which keyword to use—you can
just try both at once!
John OR Jim
cat OR feline
soccer OR football
College OR University
• Your search results will show items
containing either of the search
• Gold shaded area represents
search results (it’s all gold).
Here’s another example using “OR”:
“NOT” lets you exclude books or articles from your search results that you
know won’t be useful. Here are a few examples:
Try visualizing a “NOT” search like
If I’m interested in rock music and I
search “rock,” I may get a lot of search
returns that relate to geology,
something totally unrelated to rock
music. But I can get rid of all those
useless geology search returns by
searching: rock NOT geology. This
means I have a lot fewer search
returns to weed through.
Bigfoot NOT truck
forest NOT (tropical OR rain)
Rock NOT geology
Cats NOT Dogs
• Search results containing
only information on cats, but
nothing on dogs.
• Purple shaded area
represents search results.
Another example of using “NOT”
Just to be clear, you don’t need to capitalize Boolean
operators in order for them to work. They’re only
capitalized in this tutorial for emphasis.
Also, the “AND” is assumed by some search engines and
databases, meaning the search engine/database
automatically puts an “AND” in between each word in your
Let’s look at two final operators, both of which can be very
Quotation marks are extremely useful. As we mentioned before, search
engines and databases may automatically put an “AND” in between each of
the words in your search string. So if you search…
…the database will actually search:
King of the hill
king AND of AND the AND hill
So how do we only search for books or articles that include the full phrase
“King of the hill”? We use quotation marks around the phrase:
“King of the hill”
Now only items that use the full phrase will appear in our search results.
This is especially helpful with full names. If we searched Henry Miller
without quotation marks, every article or book that includes the names
Henry and Miller will show up in our returns. By putting “Henry Miller” in
quotation marks, we weed out the useless stuff.
The asterisk is also called a wildcard. It’s also called a truncation mark.
This is an extremely useful Boolean operator, and it’s well worth learning
how it works. Basically, it acts as a substitute for any conceivable
combination of letters. Let’s look at an example:
If I was interested in feminism in professional sports, I might try a search
like this: feminism AND professional sports.
Unfortunately, that search may miss a couple of articles I’d find really useful.
Why? Because “feminism” would have to appear in any book or article in
my search returns. What if a great article exists in a database, but it uses
the word “feminist” instead of “feminism” in the article record? It might not
show up in my search returns.
Instead, I might search: femin* AND professional sports.
The asterisk (*) lets me search every possible ending to “femin” all at once.
Another example: civil* would pull up “civilization,” “civilizing,” “civil,” and
every other word that starts with “civil”.
Now let’s create a few search
strings using Boolean operators.
“I want to find information about cloning
To find information on this topic, you could
actually try a couple of different search strings.
Here are two possibilities:
Cloning AND human
“Brad Pitt” OR “Angelina Jolie”
“I want to find information about either Brad
Pitt or his wife, Angelina Jolie.”
mummies NOT Egypt
“I want to find information about mummies,
but not mummies in Egypt.”
“I want to find information about behavior in
Consider: Is there more than one search term
we could use to find cat-related information?
Behavior AND (cats OR felines)
Consider: which software programs help you create
“web site design” NOT (Dreamweaver OR “Front
“web site design” NOT software
“I want information on designing web sites, but
not on specific web design software