Journal articles are the academic's stock in trade, the basic means of communicating research findings to an audience of one’s peers. That holds true across the disciplinary spectrum, so no matter where you land as a concentrator, you can expect to rely on them heavily.
Regardless of the discipline, moreover, journal articles perform an important knowledge-updating function.
In some fields, especially the sciences, where knowledge accrues rapidly, and where lab or research findings must be disseminated quickly, journal articles reign supreme.
Textbooks and handbooks and manuals will have a secondary function for chemists and physicists and biologists, of course. But in the sciences, articles are the standard and preferred publication form.
In the social sciences and humanities, where knowledge develops a little less rapidly or is driven less by issues of time-sensitivity, journal articles and books are more often used together.
Not all important and influential ideas warrant book-length studies, and some inquiry is just better suited to the size and scope and concentrated discussion that the article format offers.
Journal articles sometimes just present the most appropriate solution for communicating findings or making a convincing argument. A 20-page article may perfectly fit a researcher's needs. Sustaining that argument for 200 pages might be unnecessary -- or impossible.
The quality of a research article and the legitimacy of its findings are verified by other scholars, prior to publication, through a rigorous evaluation method called peer-review. This seal of approval by other scholars doesn't mean that an article is the best, or truest, or last word on a topic. If that were the case, research on lots of things would cease. Peer review simply means other experts believe the methods, the evidence, the conclusions of an article have met important standards of legitimacy, reliability, and intellectual honesty.
Searching the journal literature is part of being a responsible researcher at any level: professor, grad student, concentrator, first-year. Knowing why academic articles matter will help you make good decisions about what you find -- and what you choose to rely on in your work.
Think of journal articles as the way you tap into the ongoing scholarly conversation, as a way of testing the currency of a finding, analysis, or argumentative position, and a way of bolstering the authority (or plausibility) of explanations you'll offer in the papers and projects you'll complete at Harvard.
