An annotated bibliography describes the field of research on a topic and should include sources that reflect the range of approaches to the subject.

There are four main types of annotations.

Descriptive

A descriptive (also called an indicative) annotation gives a brief overview or summary of the text. This can include a:

• Description of the contents and a statement of the main argument (i.e., what is the book about?)
• Summary of the main points; can include topics or chapter titles

Evaluative 

An evaluative (also known as a critical) annotation includes an analysis of the work.  In addition to a summary of the essential ideas, it provides judgments—negative, positive, or both—about their quality.  This kind of annotation usually begins with broad comments about the focus of the source, then moves to more details, and then to your evaluative comments.  Some useful points to consider are the:

• Work's contribution to the literature of the subject
• Way it compares to other works on the topic
• Author's qualifications for writing the work / authority of the publisher
• Author's bias or tone
• Strengths and weaknesses of the text
• Accuracy of the information
• Intended audience, level of difficulty
• Usefulness of the text for your research project or for further study

Informative

An informative (also called summative) annotation also provides a summary of the source.  Unlike the indicative annotation, however, it gives actual information (hypothoses, proofs, other data) about the source.  It contains no statements about the source's relevance to your paper or critical remarks evaluating the source's quality.  An informative annotation includes the author's:

• Thesis
• Argument or hypothesis
• List of proofs
• Conclusion or results

Combination

Most annotated bibliographies are a combination of the above, and include one or two sentences summarizing or describing content, in addition to one or two sentences providing an evaluation.

Always consult your instructor about the format of an annotated bibliography for your class assignment. This guide provides you with examples of various styles, but they may not be exactly what your professor has in mind.