Boolean searching allows you to combine your keywords and related terms with operators such as AND, OR, and NOT to find the most relevant results possible from your search.
AND is used to tell the database that you want it to find all of the terms that it links. If you want the database to find articles that mention both social media and the online classroom, you would link these terms with AND, like this: social media AND online classroom. This NARROWS your search, and is an important concept to remember for when you receive too many items in your search results.
OR is used to tell the database that you want it to find any or all of the terms it links. The results could have just one of the terms, or it could have both/all of the terms it links. Because it will search for any of the terms, rather than all, OR will expand your number of results. This makes OR especially useful when you are searching for synonyms. OR broadens your search, and is an important concept to remember when you do not retrieve enough items in your search results. For example: social media OR Facebook OR Twitter
NOT is used to tell the database that you want to exclude results that mention a particular word or concept. For example, if you wanted to exclude articles focused on online education and social media in community colleges, the search statement would be: (social media OR Facebook OR Twitter) AND (online classroom OR distance education OR online learning) NOT community college
For more information on AND, OR, and NOT see: How should I search in a database? from Ronald Williams Library.