This is a community of massively open online classes. Most of these classes are free to the general population, and delivered online. Most of these classes are self-paced, although some of them are led by an instructor. Enrollment in these classes is unlimited...hence the term massively open. Some of these classes have enrolled over 20,000 students around the world!
You can sign up and begin most of these classes at any time. Some will require that you pay a fee and enroll through the provider's site. If you have questions, many of the learning providers are available through Knoitall.