Primary sources are first-hand accounts of an event or time in history. Unlike secondary sources (such as journal articles), primary sources don't provide any analysis or interpretation. Think of them as a sort of raw material, not yet evaluated by another person.
Primary sources are especially useful for researchers because they reveal how certain topics and ideas were understood during a specific time and place. The primary sources that you might use in your research can vary a lot based on your field of study.
In historical studies, these include sources of information from people who were participants or direct witnesses to the events in question. Examples: