It is important to differentiate between scholarly and popular sources of information when doing college level research. How can you tell the difference?
Scholarly books are written by scholars for other scholars/researchers to use. Scholars generally work at universities and colleges. Therefore, scholarly books are produced by universities and colleges. How can you tell if a book is produced by a university or college? Look at the publisher: if the publisher includes the name of a school like "Oxford University Press" or "University of Michigan Press," you know that it is a scholarly book. Scholarly books are written for a scholarly audience, meaning an audience that has a specialized knowledge of a subject that is not shared by the larger public: in other words, the author assumes you already have a strong academic background in the topic.
Popular books are published for a much wider audience by companies like HarperCollins, Macmillan, Penguin, Random House, and Simon & Schuster. These books can be seen as casual or recreational reading: they can still be informative and educational, but the target audience is very broad.
Scholarly or peer review articles are also written by scholars for other scholars/researchers to use. Like scholarly books, they assume the reader has a strong academic background in the topic. What does "peer review" mean? If you a write a research manuscript (paper) and send it to a journal you feel might be interested in publishing it it will be reviewed by the journal editor. If the editor thinks it is of interest they will send your manuscript out to a jury of experts ("peers") who look the manuscript over and give the editor feedback on whether they think it should be published or not. The idea is that if five or six experts agree that a piece of research is solid and important and trustworthy there will be a degree of quality control that other researchers can rely on when they read the final published product. So how do you know if the article you are looking at is peer reviewed? What makes your college papers different than what you wrote in elementary school? The difference between a college paper and something from a third grader is that a college student has to cite their sources in a bibliography, footnotes, endnotes, etc. Therefore, if you are reading an article and it includes citations you have yourself a peer reviewed scholarly article.
Non-scholarly articles include obvious examples such as the articles you would read in People Magazine or Sports Illustrated. While magazines like these are generally seen as recreational reading, there are publications like The New Yorker or The Wall Street Journal which are important and highly regarded sources of information but do not include citations and are, therefore, not considered scholarly sources.