MOOCs (Massive Open Online Courses) are online courses that are open to unlimited participation and are accessible via the internet. They involve traditional course materials like filmed lectures, readings, and problem sets, as well as interactive forums for community interaction. There are two main types of MOOCs - XMOOCs which focus on content delivery and automated testing, and cMOOCs which emphasize collaboration. MOOCs provide free education to learners but have disadvantages like limited engagement and possible academic dishonesty. They are best used as a supplement to traditional education or for extracting open educational resources.