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.
Massaro, John. "Press Box Propaganda? The Cold War and Sports Illustrated, 1956." Journal of American Culture, vol. 26, no. 3, 2003, pp. 361-70. Academic Search Complete, search.ebscohost.com/login.aspx?direct=true&AuthType=ip,cpid&custid=s1088435&db=a9h&AN=10351835&site=ehost-live.
Frimer, Jeremy A., and Linda J. Skitka. “Are Politically Diverse Thanksgiving Dinners Shorter than Politically Uniform Ones?” PLoS ONE, vol. 15, no. 10, Oct. 2020, pp. 1–27. Academic Search Complete, doi:10.1371/journal.pone.0239988.
Jackson, Michael, and Paul Lieber. “Countering Disinformation: Are We Our Own Worst Enemy?” The Cyber Defense Review, vol. 5, no. 2, 2020, pp. 45–56. JSTOR, www.jstor.org/stable/26923521.
Margolin, Sara J., et al. “E-Readers, Computer Screens, or Paper: Does Reading Comprehension Change Across Media Platforms?” Applied Cognitive Psychology, vol. 27, no. 4, July 2013, pp. 512–519. Academic Search Complete, doi:10.1002/acp.2930.
Every time you refer to information that is not your original conclusion and is not common knowledge, you must give credit to where that information comes from. (Whether it's quoted OR paraphrased!)
You will typically note in parentheses the author's/authors' names and relevant page number, if available.
When there's no author, your citation starts with the article title, and your in-text citation will use that.
It's all about making it easy for your reader to make a one-to-one connection by just skimming down the left edge of the Works Cited page.