The definition of a MOOC (Massive Open Online Course) is an open access study course available over the Internet, without charge, to the public.
The popularity of MOOC’s has skyrocketed in past decade, and a number of ventured back companies have sought to cash in by offering a paid upsell for course completion “certification”. For example edX, one of the largest players in the space, offers a free six week course through Boston University called Strategic Social Media Marketing. If you want to get an official certificate of course completion that costs $399.
Some MOOCs are entirely free, charging students nothing to participate. Like Stanford University’s Introduction to Mathematical Thinking administered through Coursera, another large MOOC aggregator. Several non-profits, like the Khan Academy, which has more of a K-12 focus, are also active in the MOOC space.
Most MOOC courses are very large, with thousands of online students participating. A MOOC is all about scale, hence the “massive” or “M” part of its name. Students taking MOOC’s from traditional Universities may or may not receive college credit.