Zach Sharrow: Hello everyone. This is LMU Health Sciences Librarian, Zach Sharrow, here to tell you about Boolean operators. So let's say, I'm working on some research for a paper. I'm at the database search screen, and I see a little menu drop down that looks like this. What are those things? Those are Boolean operators. They can help you get better search results. They're named for George Boole, a 19th century English mathematician, who it turns out had a lot of great ideas about computers before we even had computers. So, what do they do? Boolean operators help you define the set of results that you want the database to show you. Let's look at them one at a time.

Start with a bunch of things that have characteristics. They don't all have exactly the same set of characteristics, but there's some overlap. Let's say you have some pirates, some ninjas, and some pirate ninjas. And, I guess they live inside a computer. I can ask the computer to show me everything that's a pirate or everything that's a ninja. Connecting those two terms with the "AND" operator narrows my results to only those things that are both pirates and ninjas. This also works with more than two terms. Maybe, I'm looking for pirate and ninja and cephalopod.

On the other hand, if I connected those two terms with the "OR" operator, I get everything that has at least one of those characteristics. In this case, that's everybody. That's going to make my results broader than if I just search for one or the other. Again, this works with more than two terms.

"NOT" is a way of excluding something. This is the only one where order matters, whatever comes after the "NOT" gets excluded. So if I search for a pirate "NOT" ninja, anything that's a ninja gets left out. Notice that this isn't the same thing as just searching "pirate." If I reverse the order, it's the pirates that walk the plank, bucko.

You can combine operators in basically any combination you want, setting off groups of things with parentheses like algebra. This can be very effective if you know what you're looking for, but it can get complicated pretty quickly.

That brings us to the end of the introduction to Boolean operators, powerful tools that help you build better searches. And always remember, the library is here to help.