Put simply, an annotated bibliography is a list of citations for resources and materials consulted for a research project. The resource is cited, and the citation is accompanied by a brief description, or annotation, of the resource. The description may also include a very short analysis or evaluation of the resource in question, stating the resource's validity, authority, and quality. As such, annotated bibliographies generally lend a critical or analytical aspect to a research project.
Examples of annotated bibliographies:
The OWL at Purdue: Annotated bibliography examples
EasyBib: Annotated Bibliography Format & Examples