An abstract is a short and informative outline of your work. It usually includes the following sections
1-4 sentences to introduce your work so that the reader has some context
1-4 sentences describing what you did (research question and methods)
3-6 sentences on your major findings to date; and
1-3 sentences describing what your work means to others.
An abstract tells the reader what they need to know to understand the big picture of your project.
An abstract is not a summary. A summary appears at the end of a piece of work, and is a restatement of the important findings and conclusions.
Abstracts are found at the beginning of journal articles, research papers, reports, theses, and dissertations. Abstracts can also be used to describe a talk or poster presentation at a conference.
Adpated from Dr J. Mark Tippett's "How to Write an Abstract"