A bibliography is a list of sources (e.g., books; journal or magazine articles; websites) one has used for researching a topic. Bibliographies are sometimes called "references" or "works cited" depending on the style format you are using. A bibliography usually just includes the bibliographic information (e.g., author; book or journal title; article title; date; publisher).
An annotation includes both a summary and evaluation of each source you review.
Therefore, an annotated bibliography includes both the citation and annotation for each source you review. Depending on your assignment, your annotations may include one or more of the following types of writing:
Your annotated bibliography may include some of these, all of these, or even others. If you're doing this for a class, you should get specific guidelines from your instructor.
Information taken from the Annotated Bibliographies created by the OWL Purdue Online Writing Lab.
Annotated Bibliographies [section 5.132 of MLA Handbook, 9th Edition]
"Style a source in an annotated bibliography just as you would one in a list of works cited, and then append an annotation to the end of the entry, indented an inch from the start of the entry (to distinguish it from the half-inch hanging ident of entries composed of more than one line).
Annotations describe or evaluate sources or do both. They should not rehash minor details, cite evidence, quote the author, or recount steps in an argument. Annotations are generally written as succinct phrases.
EXAMPLE 1
But annotations can also be given as complete sentences.
EXAMPLE 2
In an annotated bibliography, the annotations should generally be no more than one paragraph. If however, you need several paragraphs, indent each one but do not add an extra space between paragraphs. Follow your instructor's guidelines on the use of phrases or full sentences and the length of annotations.
The list should be titled Annotated Bibliography or Annotated List of Works Cited. Writers may organize the bibliography alphabetically by author or title (as for normal list of works cited), by date of publication, or by subject."
If your instructor has different guidelines than those outlined above, follow your instructor's requirements.