The Abstract is extremely important because it helps readers decide what to read and what to pass over. The idea of the Abstract is to give readers an honest evaluation of the report's content, so they can quickly judge whether they should spend their valuable time reading the entire report. This section should give a true, brief description of the report's content. The most important purpose of the Abstract is to allow somebody to get a quick picture of the report's content and make a judgment.
Since an Abstract is a brief summary of your report, its length corresponds with the report's length. So, for example, if your report is eight pages long, you shouldn't use more than 150 words in the Abstract. Generally, Abstracts define the report's purpose and content.