An abstract is a short summary of a research paper. It is not part of the actual text and must be included at the very beginning of your work. You write an abstract to give a brief account of the most important information relating to the research background, structure, method, data analysis, and results of your research paper. An abstract must never be confused with the cover text (blurb) of a novel. While the blurb is all about creating suspense, the opposite is true when you write an abstract: Making it very clear early on what your results are will help the reader evaluate the relevance of your paper.
The length of the abstract should not exceed one or two pages and must never be confused with the conclusion. In contrast to the conclusion, the abstract can stand on its own. It does not show up in the structure and the table of contents of your thesis.