An annotated bibliography is an organized list of sources, each of which is followed by a brief note or "annotation."
These annotations do one or more of the following:
describe the content and focus of the book or article
suggest the source's usefulness to your research
evaluate its method, conclusions, or reliability
record your reactions to the source.
From the University of Wisconsin-Madison's Writing Center
*How to Prepare an Annotated Bibliography - Cornell University Library