The array of articles that you select should reflect the breadth of the topic that you have selected, rather than a handful of articles which represent only one perspective. The annotated bibliography should be compiled in accordance with a recognized citation style, as defined by your instructor. It is up to you to confer with your instructor about the style appropriate for your assignment. To begin your annotated bibliography, then, you'll need to know how to write an abstract. An abstract is the backbone of a bibliography.
Abstracts are summaries of articles or books.
You may have come across abstracts in doing research for your review. Though both present an overview of the article, they differ in purpose and in amount of detail. They sound much like a prospectus, giving the topic , rationale and purpose of the article. They do not contain conclusions. Because of its general nature, the descriptive abstract cannot serve as a substitute for the article itself.