First-hand information (primary source) - This is when you are directly involved in the event. There is no one between you and the actual event; you were there. This is the most desirable source of information.Some primary sources: If you weren't actually there, you can sometimes get film footage or sound recordings of an actual event; this could count as a primary source (though there are still things that might be missed, as recording devices have their limitations). Surveys can be first-hand information, since you are the first person to ask people their opinions on the issues you are researching. You need to consider the reliability of first-hand information - while your source may tell you what he/she thinks is the truth, it is possible for your source to be incorrect. You should always try to verify first-hand information with other sources.
Second-hand information (secondary source) - This is when someone else, who was directly involved in the event, tells you about it. There is one person between you and the actual event; this means that person is giving you his or her interpretation of the event; they might not see or hear everything, or they might explain it to you in such a way that your understanding of the event is different than what actually happened. This is the second best source of information. You need to consider the reliability of second hand sources carefully; it is always good to gather information from more than one source to make sure they all match.
Some secondary sources: autobiographies, some newspaper and magazine articles (when the author was there and is writing about it), interviews with primary sources
Third-hand information (tertiary source) - This is when someone who was actually there tells another person, and that second person tells you about it. This is the least desirable, but most common, source of information for research. There are two people between you and the event, each one of whom is interpreting the event in his or her own way. You should NEVER rely on information that is beyond third-hand; it is not reliable. You need to consider the reliability of third hand sources carefully; it is always good to gather information from more than one source to make sure they all match.
Some tertiary sources: biographies, most encyclopedia articles, most newspaper and magazine articles, some TV shows and movies