A bibliography is an organized list of sources (journal articles, books, government documents, websites, etc.) on a specific subject area. Citations in this organized list include the bibliographic information of each source, such as the author, title, and publication information.
An annotation is a summary, description or evaluation.
An annotated bibliography is similar to a bibliography, with the difference being that each citation entry includes a brief description and assessment of the cited source - an annotation. Annotations are short paragraphs which are usually between 150 and 200 words, however, depending on your purpose they may be substantially longer.
An annotated bibliography can serve many purposes: