Those who catalog information and create research reference materials also use abstracts. Most information-retrieval systems can scan the key words in an abstract and retrieve the source it is based on.
Depending on the discipline in which you are writing, you may be asked to write an abstract for a research report, seminar paper, or a scholarly paper. Many graduate theses and dissertations require them.
Because abstracts help readers decide whether they want to read the original source, the content is quite compressed. Your abstract should contain only a few sentences, perhaps only three to five. You should include the key words that reveal the major idea of the original material to identify the field of study involved.