Boolean searching allows users to combine keywords with operators (or modifiers) such as AND, OR, and NOT to further produce more relevant results. To better understand a database search, like the kind of searching you will be doing with CINAHL or PubMed, it may help to better understand how a Boolean search can achieve more targeted results for your research.
The Boolean operator NOT will filter some unwanted articles by excluding those with a particular word or phrase. This is especially useful if you have a word that can mean two different things. For example, if you're interested in articles about the part of the human heart called the atrium, but not about articles about Atrium Health, the hospital system, you could try a search like: "atrium NOT hospital." This may make things tricky, however, as you may be missing articles about heart surgery within Atrium Health, so be careful how you use this operator!
This is where things get a bit complicated. But don't worry! Nesting is a way you can target your search and still catch the main ideas you're interested in discovering. For example, you may be interested in research on how caffeinated beverages like coffee or tea can affect your mood. You're not particular about whether the articles focus on coffee or tea, and you know that "mood" and "emotion" are words related to each other, so you want them both included in your search. You can break down this search into sections by using parenthesis. For example, you could do a search like this:
(coffee OR tea) AND caffeine AND (mood OR emotion)
Remember your high school algebra and the order of operations? Whatever is in the parenthesis gets solved first, right? This is similar, in a way, in that the terms in the parentheses are searched on their own first. The database you are using will search for articles that 1) have the words "coffee" or "tea," 2) search for articles within those results that also have the words "mood" or "emotion," then finally 3) search for articles that also have the word "caffeine."
The Boolean operator OR will expand your search. For example, if you're doing a search for articles on favorite furry pets, you could try a search like this: dogs OR cats. You're not particular about which one is the focus of the article, so you want to all of the ones that mention either dogs or cats.
If you wanted to do a search using an exact phrase, you'd put that phrase in quotation marks. This is when you want to make sure the words of your search are in the right order. For example, if you wanted to find information on chicken pox, you could be retrieving many articles on chickens, and many articles on several kinds of pox, but not necessarily chicken pox. By putting the term "chicken pox" in quotation marks, you are only pulling up articles that have those words in that order.
(And yes, I know it's technically "chickenpox," but for the purposes of this example, just go with it.)