An abstract is a brief summary of a research article, thesis, review, conference proceeding, or any in-depth analysis of a particular subject). It is often used to help the reader quickly ascertain the papers purpose and serves multiple purposes, such as allowing readers to get the gist or essence of the paper or article quickly, preparing readers to follow the detailed information, analyses, and arguments in the full paper, and helping readers remember key points from the paper. An abstract should be intelligible on its own, without a reader having to read the entire paper. It is usually a paragraph long, containing around 150-250 words. An abstract should be the last thing that is written, once the conclusions of the paper are clear. Different disciplines may have slightly different approaches to abstracts, but they should all contain key elements such as the research purpose, the relevance or importance of the work, and the main outcomes.