This document defines and describes Massive Open Online Courses (MOOCs). It states that MOOCs are open online courses available to unlimited participants via the web for free. They provide an affordable way to learn new skills and pursue lifelong learning. The document outlines that MOOCs started with MIT's OpenCourseWare initiative in 2001 and were popularized in 2008. They allow for teaching in a video format, openly accessible content from top universities, and online interaction between learners and teachers.