Once you have formulated a good research question/topic, you will need to pick out the words and phrases that are most important to your search. This is called identifying the main concepts and is necessary for searching databases.

For example, let's say your research question is:

Should the use of marijuana for medical purposes be legalized?

Looking at the question word-by-word, let's see which words will actually be useful when you search for information:

Should the use of marijuana for medical purposes be legalized?

The useful words/concepts are in red. Notice the words chosen have some integral meaning - and they each describe a specific part of our question. Skip words that are too common or generic (should, use, be, purposes, etc.)

Now let's brainstorm ways we can design searches in databases to retrieve articles on your topic. Think about your question and words creatively - how else can you express the same idea? Are there any other words that may be useful?

For example:

marijuana = cannabis
medical = therapeutic
legalized = law

Once you have identified additional words, you can also create search statements! These are called boolean operators, which include AND/OR/NOT between different words. Look:

cannabis AND medical AND law
cannabis OR marijuana AND medical
marijuana AND therapeutic AND legal

Try it with truncation:

If you want the database to search for various forms of the same word, you can use truncation (* = the asterisk). To use truncation add an asterick to a shortened version of your search term. The asterisk is a commonly used wildcard symbol that broadens a search by finding words that start with the same letters. Use it with distinctive word stems to retrieve variations of a word. 

cannabis AND medic* AND law
marijuana AND therap* AND legal*
cannabis and therap* and legal*

Example:

legal* will retrieve

legal
legally
legalized
legalize
legality
and anything else that starts with legal

Choosing the Information You Need