Boolean searching involves building research concepts and terms with, most often, the terms AND, OR.
When using these terms, always remember to capitalize them. So, if I conducted a search within Pathfinder or Google, I could do something like:
mental health AND coronavirus.
Now, in a Pathfinder search via the library, for example, that will yield a fairly robust list, as seen here.
However, I could tweak that a bit with the following:
mental health AND (coronavirus OR covid-19)
Notice that I expanded the concept of coronavirus to the more specific covid-19 by using OR to connect these synonymous terms. Use OR when you want to indicate the desire to search for various expressions of a term. Also, note that I placed the synonymous terms within the confines of parentheses. With that search string, the research tool has a better idea of what bits of the query need to remain together in certain relationships with one another.
Try mixing up your own terms with a combination of AND, OR terms to build more complex search strings! As always, we can help with that as needed!