To start searching, you can simply enter your keywords in whatever database or search engine you’re using. However, to unlock the full potential of the library databases, a powerful tool is available to you: Boolean operators.
OR combines your synonyms and related terms to find documents that contain any or all of the words. It broadens your search and produces more results.
Your results would include all of the above documents.
AND combines your different concepts to find only the documents that contain all of the keywords. It narrows down your search and produces fewer and more relevant results.
Your results would include only the documents outlined in green.
NOT followed by a keyword will exclude all the documents that contain that particular word. It is a way of avoiding unrelated search results.
Use it with caution as you may miss out on potentially useful material.
Your results would include only the documents outlined in green. Note that you may miss out on some relevant information in the document that talks about both heroin and other drugs.
Download this keyword chart to use with the Boolean operators AND and OR (see an example of a filled-out chart).