This is a self-contained paragraph which encapsulates the entire study: purpose, methods, results, interpretation. It is normally no more than one double-spaced page and its page is separate from the Introduction. The abstract appears first but it is often best to write this last, after all else is done. It is essentially a separate, miniature version of the whole paper rather than a part of it. It must include a brief introduction, description of key methods and results, and some interpretation.