An abstract is a short summary of a longer piece of writing that highlights its key points. There are typically two types of abstracts: descriptive abstracts summarize the purpose, methods, and scope without providing results or conclusions, while informative abstracts also communicate the results and conclusions in addition to the purpose and methods. A good abstract is concise, uses well-developed paragraphs, follows the structure of the original work, and adds no new information. To write an effective abstract, one should reread the original work to identify its key components and write a rough draft without copying directly from the original.