An abstract is a precise outline of a scientific work in order to give the reader an overview of the statements of the publication at the beginning.
General characteristics of an abstract are:
- it should abstain from any evaluation
- it should be as short as possible
- it should have a clear, comprehensible language and structure
- it should contain all essential facts and it should reflect exactly the contents and opinion of the original work.
https://en.wikipedia.org/wiki/Abstract_(summary)