Academic study begins by examining the work of scholars that have come before us. While it is essential that your work is written in your own words, it is equally important that proper credit is given to the authors we have studied and learned from. We do this by citing our sources, and quoting or paraphrasing the original writers when appropriate.
A citation credits the source of your information. Cite the sources of your information according to the rules of your professor's preferred style guide (MLA, APA, etc.). Even if your work is wholly written in your own voice, you need to cite the source of your information to give credit to the original scholars and to show the thoroughness of your research. When another author's words or ideas are presented in your work, they need to be quoted or paraphrased.
Example:
Quoting, Paraphrasing and Summarizing at Purdue OWL
Quoting and Paraphrasing at The University of Wisconsin
Quoting Materials at Plagiarism.org
An annotated bibliography is a list of citations to books, articles, and documents. Each citation is followed by a brief (usually about 150 words) descriptive / evaluative paragraph, called the annotation. The purpose of the annotation is to inform the reader of the relevance, accuracy, and quality of the sources cited.
Check out Cornell University Library’s guide to writing an annotated bibliography for detailed information.