An abstract is the first page of a lengthy report. Abstracts are typically a summary of the report. However, there is a certain format to an abstract. Usually they are written for a report where a study was done. The report itself will have a certain format to that. Each section is included in a one or two-sentence summary in the abstract. You should include information about the background of the topic. Also, include the participants and method of conducting the study.
Then the abstract should include information about the results and conclusion. The abstract itself is usually shorter than a half page of type. The writer should refrain from using too many descriptions from the report. Instead, they should short summaries.