NOTE: This is general information about annotated bibliographies. Always defer to your professor and the course syllabus as there may be specific requirements for the class that differ from this information.
A bibliography is a list of sources (books, journals, etc.) you used for researching your topic. Bibliographies are sometimes called "References" or "Works Cited." A bibliography includes the bibliographic information (i.e., the author, title, publisher, etc.).
An annotation is a summary and/or evaluation.
An annotated bibliography includes a summary and evaluation of each of the sources you used for researching your topic. Your annotations should do the following.
For more help, see the Purdue OWL's page on paraphrasing sources.
Generally, annotations are one paragraph, with a goal of concise and explicative annotations. Usually one or two sentences summarizing or describing content, one or two sentences providing an evaluation, and a final sentence or two on your reflection.
For the bibliographic information, cite your sources according to the format required. Whichever format you use, be consistent!
The annotations for each source are written in paragraph form. The paragraph should contain a statement of the work's major thesis, from which the rest of the sentences can develop.
Usually annotated bibliographies are arranged alphabetically although sometimes they are organized chronologically, by format (books, journals, etc...), or by topic.
To learn about your topic: Writing an annotated bibliography is excellent preparation for a research project. Collecting sources for a bibliography is useful, but when you have to write annotations for each source, you're forced to read each source more carefully. You begin to read more critically instead of just collecting information.
To help you formulate a thesis: The purpose of research is to state and support a thesis. So a very important part of research is developing a thesis that is debatable, interesting, and current. Writing an annotated bibliography can help you gain a good perspective on what is being said about your topic. By reading and responding to a variety of sources on a topic, you'll start to see what the issues are, what people are arguing about, and you'll then be able to develop your own point of view.
Adapted from the Purdue OWL's "Annotated Bibliographies" page and the Lucy Scribner Library, "Writing an Annotated Bibliography."