Primary Sources — Produced at the time of the events they describe or created by authors with firsthand experience of those events. The content of primary sources is entirely original and does not typically include interpretation or evaluation of other sources.
ex. Scholarly articles (with original research), diaries, newspaper articles, theses, works of literature, correspondence, autobiographies, legislation.
Secondary Sources — These sources analyze and interpret primary sources, typically in order to make some sort of argument. Secondary sources could be published any time after the publication of the primary sources they refer to, from almost immediately after, to hundreds of years later.
ex. Articles or books that interpret original research or creative works, biographies, historical analyses.
Tertiary Sources — Sources that compile information from secondary and primary sources. They tend to be objective and factual.
ex. Encyclopedias, almanacs, bibliographies, and other reference sources.
It can be difficult as a new college student to know which sources are the most credible and useful for your purposes. The T.R.A.A.P. Test (Timeliness, Relevance, Accuracy, Authority, Purpose) is one way to remember all the questions you should be weighing when evaluating an article.
When you reach the stage of research where you're evaluating the quality and usefulness of sources, keep in mind that not all sources are scholarly, or written with a scholarly audience in mind. Generally, you'll want to avoid popular sources that are written for general audiences and often have agendas or profit motivations influencing the information they're presenting.
Bonus: A third less common source you may encounter are those in trade publications. These are journal or magazine articles written and published by professionals in a specific field for other professionals. While potentially very informative, trade sources aren't considered scholarly because the content is not necessarily original research or peer-reviewed.
Academic Search Premier is a general use database and therefore contains academic information from many different subject areas. It's a great place to start looking for scholarly articles when you're not sure where to begin. Below is a map of the basic parts of an article page as it would appear in this database.