An abstract is a stand-alone statement that briefly conveys the essential information of a document, whether it is an article, report, book, or some other form of writing. Often abstracts are published alone in abstract journals or in on-line databases. Thus, an abstract might serve as the only means by which a researcher may ascertain the information in a document. Moreover, a researcher might decide whether to read the document based on the abstract alone. Because of this need for self-contained compactness, an abstract must convey the essential elements of a document.

The descriptive abstract tells what a paper includes but does not summarize everything it contains. It is more of a guide to what the reader will find or a teaser than a summary of actual findings. The idea is to let readers know what the paper is about but at the same time encourage them to read it in full for the main points and conclusions. It will explain the paper's purpose and scope but not give the results or major conclusions. Typically, it is shorter than an iinformative abstract and may be only about 75 -200 words.

The informative abstract is more like a brief version of the contents of the paper. It usually summarizes the major sections and points of a paper. If it is an abstract of a scientific or technical paper, it summarizes the Introduction, Methods, Results, Analysis, and Discussion sections. A good abstract mirrors the original in its emphasis. If the original includes a lengthy discussions section and a short methods section, the abstract should devote more space to discussion and little space to methods. The typical length is 250-700 words.

An abstract should be concise, direct, and clear. The following guidelines may help you acheive the right style: