In academic research, it's important to be able to distinguish between different types of sources. These differences often are contextual, meaning that the same source might fit in different categories depending on how you are using it, and within which academic discipline you're researching and writing.
Primary sources are the raw materials of scholarship.
Secondary sources report on or interpret primary sources.
Tertiary sources synthesize and present overviews of primary and secondary sources.
Scholarly sources present sophisticated, researched arguments using both primary and secondary sources and are written by experts.
Popular sources aim to inform or entertain and are intended for a general, non-specialized audience. In academic writing, popular sources most often are analyzed as primary sources.
Research is a creative, nonlinear process. Experienced scholars will tell you that they rarely end up exactly where they thought they would when they first started out. You'll need to give yourself the time to pursue ideas, reconsider ideas in light of new information, and then craft an original, researched argument.
To be successful in college-level research, you will need to make use of the resources and services of the library. Here are a few reasons why: