It is important to be able to identify different categories of scholarly literature. Keep in mind the following definitions as you're doing your research:
Peer-reviewed (or refereed): Refers to articles that have undergone a rigorous review process, often including revisions to the original manuscript, by peers in their discipline, before publication in a scholarly journal.
Empirical study (or primary article): Aims to gain new knowledge on a topic through direct or indirect observation, research, and quantitative or qualitative data and analysis. Sections of the article may include: Introduction, Methods, Results, and Discussion.
Review article: A type of article that provides a synthesis of existing research on a particular topic. Useful when you want to get an idea of a body of research that you are not yet familiar with.
Systematic review: A methodical literature review focused on a particular research question. Aims to identify and synthesize all of the scholarly research on a particular topic in an unbiased, reproducible way to provide evidence for practice and policy-making. It may involve a meta-analysis (see below).
Meta-analysis: This is a type of research study that combines or contrasts data from different independent studies in a new analysis in order to strengthen the understanding of a particular topic.