An annotated bibliography is a list of citations of sources (books, articles, websites, etc.) used in conducting research. Each citation is followed by a descriptive summary of the information in the source, an evaluation of the quality of that information, and an evaluation of the relevance to the research being conducted.
This helpful video from Kimbel Library will further explain an annotated bibliography and how to write one.
Follow these two resources for in-depth explanations on how to write an annotated bibliography in both MLA and APA formats: