Boolean searching allows you to customize how you search for things in academic databases, and it's based on a few key pieces of syntax: AND, OR, NOT, (), and "". 

AND

When you put two terms into an academic database, AND is usually implied: You usually want both words in fluid inclusions to appear in your search results. You could just as easily write:

fluid AND inclusions

OR and ""

But let's say that I want to find something about extrasolar planets. However, there was a terminology change around 2007, after which people started using the term exoplanets. If I want articles from both eras, I can do the following:

exoplanets OR "extrasolar planets"

What this tells my database is that I don't care which term appears in the results. I just want one of them. In addition, I want extrasolar planets to be searched as a phrase. (This also works in Google with song lyrics.)

NOT

What if I'm looking for women in STEM (science, engineering, mathematics, and technology) fields, though? Try it. You'll see a lot of resources on stem cells. This is where the NOT operator is helpful:

women stem NOT cell NOT "clinical trial" NOT "stem cells"

Of course, Google and Google Scholar work differently. Instead of NOT, use a - to make it look like this:

women stem -cell -"clinical trial" -"stem cells"

Everything and ()

Or, of course, we could do this with everything (and here parentheses signify order of operations):

women AND ("stem" OR science) NOT cell NOT "stem cells"