1. The document compares four major open online learning platforms: Coursera, Udemy, Udacity, and edX. It analyzes and compares them based on their business models, course experiences, and popularity.
2. Coursera partners with universities and organizations to provide over 1,872 free and paid courses. Udemy allows individual instructors and has over 40,000 courses, some free and some paid. Udacity focuses on interactive courses for beginners in topics like computer science. EdX provides courses from universities like Harvard and schedules future courses.
3. All platforms offer free and paid courses, certificates, mobile apps, foreign language subtitles, and quizzes/