An abstract provides an introduction and overview of a full document, including background, purpose, results, and contents. It allows readers to quickly understand the key points and decide if they want to read the entire document. A summary is a condensed version of a text that outlines the central ideas, making it shorter than the original. While an abstract is found at the beginning of a research article, a summary can stand alone. The main difference is that an abstract includes purpose and results, while a summary only focuses on the central concepts.