The format and purpose of an annotated bibliography can vary; therefore, it is important that you ask your instructor for specific guidelines.

• A bibliography is a list of sources used to research a topic. A bibliography may include books, journals, periodicals, websites, and other forms of media. A typical entry includes bibliographic information such as author, title, and publication information.
• An annotated bibliography is a list of sources in which each entry offers bibliographic information as well as an explanation of the source's content.

There are two types of annotations: descriptive and evaluative. Check with your instructor to see which type of annotation he/she requires.

• Descriptive Annotations
• Evaluative Annotations

DESCRIPTIVE: (TOP)

The descriptive annotation may follow the summary format or the commentary format.

Summary

• A summary annotation provides an overview of the information offered in the source. This type of annotation should focus on the major points addressed by the work. It is not necessary to recount every topic mentioned in the publication, but the reader should have a good understanding of what is contained within the source. A summary annotation tells the reader what the source says.
• It may help to think about the answers to these questions:
  • What is the author's primary purpose or argument?
  • What are the main points of the source?
  • What topics are covered in the source?
  • If someone asked you what the source is about, what would you say?
• A summary annotation should be composed of complete sentences.

Example:

Endicott, Annabel. "Pip, Philip and Astrophel: Dickens' Debt to Sidney?" Dickensian, 63(1966): 158-62. Print.

Sidney was the inspiration of Dickens's concept of a gentleman as given in Great Expectations. Philip and Estella have parallels with Philip and Stella. Both Philips love married women of higher rank; both have friends who try to dissuade them. The words "great expectations" occur in Sonnet 21. Dickens may have been exploring the idea of the Petrarchan convention; certainly Estella resembles the Petrarchan mistress.

Commentary

• A commentary annotation should include a description of the author's argument or purpose. A commentary does not have to summarize what the source says but should briefly inform the reader what the source is about.
• A commentary annotation may be composed of verb phrases or sentences without subjects.

Example:

Endicott, Annabel. "Pip, Philip and Astrophel: Dickens' Debt to Sidney?" Dickensian, 63(1966): 158-62. Print. 

Suggests Astrophel and Stella as the source of Dickens's concept of a gentleman and exploration of Petrarchan convention in Great Expectations.

EVALUATIVE: (TOP)

An evaluative annotation should include a brief description of the author's purpose and an evaluation of the content of the source.

• To evaluate a source, think about these questions:
  • What are the author's purpose and main ideas?
  • Does the author effectively address his/her audience?
  • Does the author effectively prove his/her argument? What evidence does he/she offer?
  • Is the layout and form of the work effective?
  • Is the author dependable? What is his/her expertise?
  • Is the source current, or has it been updated?
  • Does the source contain any special features, such as charts and graphs or a useful bibliography?
  • Was this source useful to you, especially as compared to other works on the same topic?

Note: It may not be necessary to answer all of these questions. You may want to ask your instructor what you should include in your evaluation.

• Section 1.6 ("Evaluating Resources") of the MLA Handbook for Writers of Research Papers provides more details about evaluating sources or see additional Writing Guide, "Evaluating Research Resources." 
• An evaluative annotation may be written in complete sentences or verb phrases.

Example:

Schechter, Harold. "Death and Resurrection of the King: Elements of Primitive Mythology and Ritual in Roger 'Malvin's Burial.'" English Language Notes 8 (1971): 201-05.

Though Schechter reorganizes the material in an interesting format, basically his study is a reiteration of Cassier's seminal argument in The Sacred and the Profane: Modern Myth Studies. Schechter's major contribution to the debate is his recognition that Reuben sacrifices Cyrus so that the curse of death-in-life can be removed. Schechter's attempt to put Cassier's argument in a Jungian context is intriguing but not quite successful, since he must ignore important elements of the story to do so.