The abstract of a scientific paper serves two main functions: selection and indexing. Readers use the abstract to decide whether it is worthwhile to read the paper. Indexing databases search abstracts, not full texts, to find relevant results. Therefore, an abstract should both be easy to comprehend and contain all of the key words and phrases of the paper.
Most abstracts follow a strict format that includes the following sections: Background, Methods, Results, and Conclusions. Some journals may require additional sections, such as Objectives or Limitations. Always check with the professor, journal, or competition guidelines to make sure you have the required sections.