A strong abstract includes a brief summarization of the main points of your text, an overview of the methodology used, and a explanation of the sources used to construct your argument. The purpose of an abstract is different from a synopsis or preview statement in that abstracts are typically written for professional or academic papers.
It is helpful to follow the same structure each time you write an abstract. First, introduce the topic of your research, then provide a brief overview of the context of your research. Provide any historical or scientific information needed to understand your research question without going too in-depth. Then, provide a short summary of the sources used to construct your argument. It is possible that your sources have already been revealed when writing the context.
Proper abstracts always include references to other works that complement, supplement or precede yours. Next, provide the methodology. Explain the process of writing and the method used to construct your argument. The final and most important aspect of writing an abstract is providing a reason that your text is unique. Reveal what you are arguing that is new or unique, so that readers can determine whether or not the text is useful to them.