You are likely very familiar with popular sources, which are intended for a general audience, such as newspapers, magazines, and most websites. In comparison, scholarly sources are intended for an academic audience, such as professors, researchers, and college students, and they can take the form of journal articles, books, and book chapters. Trade publications are written for professionals in a specific field and are more focused than popular sources, but they are not scholarly.
Depending on your research topic and the requirements of your assignment, you may be able to use both scholarly and non-scholarly sources. Since non-scholarly sources are not subject to the same level of review before publication as scholarly sources, be sure to evaluate them before incorporating them in your project.