An abstract is a miniature version or summary of an article, paper, or thesis. It should provide a brief overview of the main sections of the article: introduction, materials and methods, results, and discussion. The length of an abstract should not exceed the journal or guidelines suggested by a university for a thesis. Commonly, the length specified is 250 words typed as one paragraph.
In How to Write and Publish a Scientific Paper (2016), Barbara Gastel and Robert A. Day suggest the abstract should a) state the principal objectives and scope of the investigation, b) describe the methods used, c) summarize the results, and d) state the principal conclusions.
An abstract is written in the past tense. Why? Because the work has already been completed.
In most cases, abstracts do not include citation of literature, abbreviations, nor include or refer to tables or figures. For example, if you repeat a long scientific word several times in the abstract, then and only then should you consider using an abbreviation. It is better to introduce any abbreviations in the introduction of the main text.
Consider making an outline of the key points of the research you are presenting. Use clear, simply and key words that will create interest for the reader. Consider who is your target readership is before you begin writing. If you can get the four points above written effectively in less than 250 words, do it, your readers will love it.
The abstract is the first part of your work people will read. Review your research and write down the key points and then create an outline stressing only the key elements – not the entire breadth of the work.