Many databases use "limiters", sometimes called "filters" to restrict search results by certain criteria.
Using limiters reduces the number of results and makes the remaining results more likely to be useful by eliminating things that will not fulfill the assignment (e.g. getting rid of things that are too old, or in a different language).
These options are often located on the database search page and/or results list as drop down menus or check boxes.
Sometimes limiters are available on an "Advanced Search" page within a database or online catalog.
Some common and useful limiters include:
date of publication
material or source type
peer-reviewed articles only
How to Use Limiters
On the initial search screen, there may be selection boxes, drop down menus, or buttons that allow you limiter choices before you even submit the first search
On the results screen, usually on the left, sometimes on the right, there will be categories of limiters to refine your results.
Know the common limiters and use them regularly:
Date of publication
Material or Source Type (e.g. peer-reviewed articles, newspapers, magazine articles, book chapters...)
Check for specialized limiters in specialized database, for example:
In PsycInfo you can limit by age group and methodology
In ERIC (an education database), you can limit by educational level
In North American Women Letters and Diaries, you can limit by Age at Marriage, or Number of Children.