An annotated bibliography is a works cited list, but each citation is followed by a paragraph of explanation and justification: why is this source one of your sources? What does it bring to your research?
You will summarize the relevant information you're getting from that source (but remember, this isn't your paper -- you are summarizing, not presenting all the information itself) as well as how this well help you in your research (by providing background information, by exploring a certain angle, by presenting a contrary idea...).
Creating an annotated bibliography is not simply an academic exercise. An annotated bibliography is a tool to help you summarize your source content and evaluate its place within your research. If a source satisfies your "usefulness" criteria, that source belongs on your annotated bibliography.
This process begins the transition from reading sources to incorporating content (ideas, quotes, paraphrasing) into your work. It is time to "make sense" of the knowledge you have gained from your research. This knowledge is the foundation on which to build your own voice, explain your methodology, discuss your conclusions, make and report on your new knowledge.
Of course, evaluation of sources goes beyond "usefulness" to the other elements of authority, credibility, currency, and purpose.
Consulted Saylor Academy's open access course on research concepts and the writing process: Research Writing in The Academic Disciplines (pdf). Annotated bibliographies have additional purposes that depend on the intent of the writer/researcher and the specific discipline.
The exact content in the annotation will depend on what your instructor asks for!
Waite, Linda J., et al. “Nonfamily Living and the Erosion of Traditional Family Orientations Among Young Adults.” American Sociological Review, vol. 51, no. 4, 1986, pp. 541-554. EBSCOhost, lscsproxy.lonestar.edu/login?url=http://search.ebscohost.com/login.aspx?direct=true&AuthType=ip,cpid&custid=s1088435&db=a9h&AN=14795430&site=ehost-live.
The authors, researchers at the Rand Corporation and Brown University, use data from the national Longitudinal Surveys of Young Women and Young Men to test their hypothesis that nonfamily cohabitation by young adults alters their attitudes, values, plans, and expectations, moving them away from their belief in traditional sex roles. This research expands and reinforces the question central to this paper of evolving attitudes to family and gender roles. Smith and Taylor’s article regarding the values of the nuclear family of the 1950s is a good contrast to the nonfamily living studied in this article.
Comment on expertise (authority)
Summary of article content
How article fits your paper (relevance)
Comment on how this source compares to or supplements other sources
Waite, L. J., Goldscheider, F., & Witsberger, C. (1986). Nonfamily living and the erosion of traditional family orientations among young adults. American Sociological Review, 51(4): 541-554.
The authors, researchers at the Rand Corporation and Brown University, use data from the National Longitudinal Surveys of Young Women and Young Men to test their hypothesis that nonfamily cohabitation by young adults alters their attitudes, values, plans, and expectations, moving them away from their belief in traditional sex roles. This research expands and reinforces the question central to this paper of evolving attitudes to family and gender roles. Smith and Taylor’s article regarding the values of the nuclear family of the 1950s is a good contrast to the nonfamily living studied in this article.
Comment on expertise (authority)
Summary of article content
How article fits your paper (relevance)
Comment on how this source compares to or supplements other sources