The main three words to use in Boolean search terms are "AND," "OR" and "NOT." These serve to inform search engines and databases about the specific request being made by a search term. For instance, searching for "lake AND fire AND thunder" will retrieve records that contain references to "lake," "fire" and "thunder," as opposed to records that contain references to any one of these terms and not necessarily to the others.
Some search engines and databases, such as Google, automatically assume the presence of a Boolean "AND." If looking to retrieve pages that do not necessarily contain all three of the search words, then "OR" should be used. This informs the database that any results with one or more of the words are relevant and should be retrieved.
"NOT" is used to refine searches by omitting certain words from the results. This is useful for informing databases of the parameters of a search. Searching for "amphibians NOT frogs," for example, will return information pertaining to amphibians other than frogs.
If using more than one of these Boolean operators in a single search, parentheses should be used. Specifically, if looking for information about the cost of either a laptop or a desktop computer, the search term should look as follows: "cost AND (laptop OR desktop computer)."