Effective and efficient database searches retrieve the items that are most closely matched to your research topic, reducing the time that you will have to spend evaluating the results. Each research tool is different, but you can find out which search strategies are supported by using the Help provided in the tool. Even Google has Help!
The common Boolean operators AND, OR, and NOT can be used to combine search terms or strings (multiple search terms) to either expand or narrow searches.
Most databases offer advanced search forms that allow you to combine concepts using Boolean operators.