Databases like JSTOR, Academic Search Complete, and others, think in terms of Boolean logic.
Boolean connectors - words like AND, OR and NOT - are the words and symbols that glue our keywords together into a search that the database understands.
Want to learn more about Boolean searching? Check out this great video from Pam Posz at Sacramento City College:
You can combine keywords using AND, OR, NOT:
AND gets more specific results because all the keywords must be in the same article. Some databases automatically insert AND between words, but it doesn't hurt for you to put it there.
OR allows you to search for synonyms or word variations. Often there are other words that mean the same as your keyword. OR allows you to search for these variations all at one time. Adding OR into a search will cause you to find MORE results because OR specifies that either word must appear in the article.
NOT eliminates unwanted words. This limits the number of irrelevant articles your search retrieves.