A bibliography is a list of resources on a topic, with each resource cited in MLA, APA, or another agreed-upon citation format.
An annotated bibliographies is also a list of resources, but includes an annotation after each entry. An annotation is a paragraph that describes and evaluates each resource. This paragraph usually includes:
For example, this is a sample annotated bibliography from the OWL Purdue Writing Lab.
Depending on your instructor's requirements, annotations may also include information about:
Different classes may have different requirements for your sources and annotations, so be sure to check your assignment sheet or ask your professor.
Since an annotated bibliography explains why each source is of interest, it is a good way of documenting your research process.
For the same reason, annotated bibliographies prepared by others can be extremely useful when you are looking for sources. One database that includes annotated bibliographies is CQ Researcher.
When citing your sources, use the citation style guide that your instructor recommends. Follow the rules set forth in the style guide, and, as usual, you should proofread your work!