An annotated bibliography is a list of research and resources on a topic, that provides not only the citation information, but also a description and evaluation of the source.
It is similar to a regular Bibliography, but each citation is followed by a paragraph of information about the source.
These are the main things to include (from UNE Factsheet: Writing an annotated bibliography):
1. Citation details (set out in the same style as a reference list item)
2. A short statement that explains the main focus or purpose of the work
3. A short summary of the theory, research findings or argument (e.g. intended audience, subjects covered, major arguments supported, research methods, conclusions reached, special features)
4. Consideration of the usefulness and/or limitations of the text for your research (e.g. reliability of the text, credibility of the author, poor features, left-out content, weaknesses in argument)
5. An evaluative comment on the work that may take into account how this work will fit into your research on a topic (e.g. critical comment, critical reflection that describes the usefulness or relevance of the information for your writing task).