Q. What is an annotated bibliography?

Here's a basic definition:

annotated bibliography

A list of sources that gives the publication information and a short description — or annotation — for each source. Each annotation is generally three to seven sentences long. In some bibliographies, the annotation merely describes the content and scope of the source; in others, the annotation also evaluates the source’s reliability, currency, and relevance to a researcher’s purpose.

The Purdue OWL (Online Writing Lab) has more information and some samples of annotated bibliographies.