So how exactly do you compose an annotation? Well, a good annotation is made up of two parts:
Your summary of a source is basically a quick run through of the work's topic and main points. You want to give a concise overview of the source, rather than a detailed account. The length of your annotations may vary, but the summary is usually less important than your critical assessment of the work and will be shorter. You want to dedicate more space and effort to evaluating the source.
There are several different factors that can go into evaluating a source (they will be discussed in more detail on the second page of this guide) but it is generally a good idea to start by providing a scholarly or historical context for the work. Discuss the thesis and conclusions that the author reaches and where those fit into the general scholarly thinking regarding the topic. You might also consider the author's qualifications and past publications as well as how the source relates to your own work.
Your annotated bibliography can be organized in several different ways, depending on your focus and what makes the most sense for your research. As long as your professor hasn't assigned a specific kind of order, you can use any of the following:
Alphabetical - a simple alphabetical structure by the author's last name gives a clear, easy to follow order.
Chronological - organizing chronologically by publication date allows you to track developments in the field over time. Working almost like a concept map, this structure allows you to see when and why the general consensus in a field starts to change and what kinds of ideas and arguments develop as a result of that change.
Topic/Subtopic - Like an alphabetical structure, organizing by subtopic gives you a clear and easy to follow layout with the added benefit of linking together related ideas and concepts.