The 9 most popular online courses people are taking on Coursera from Stanford, Yale, and Princeton

• Millions of students of all ages use Coursera to learn something new, whether for personal enjoyment or professional advancement.
• The online classes are completely free to audit, or, you can pay an affordable monthly fee in order to receive an official course certificate of completion.
• The most enrolled classes on Coursera include Stanford's Machine Learning, Yale's The Science of Well-Being, and the University of Michigan's Programming for Everybody.

With people worldwide staying at home, the question of how to keep busy inevitably comes up.

Online learning platforms like Coursera, Udemy, edX, and Skillshare offer a refuge, both from the boredom of sitting indoors all day and the anxiety of everything going on in the world right now. E-learning sites like these aren't new, but they're even more important now because of the resources and learning opportunities they offer to students of all ages.

Coursera offers individual courses, specializations, professional certificates, and full online degrees from top universities and companies. They're free if you audit the course (meaning you won't get access to certain course materials like graded assignments, and you won't receive an official certificate of completion), but if you want to earn a course certificate, you can pay an affordable monthly fee.

Through the end of December 2020, 100 of these courses are completely free. They include all course materials and a course certificate.

Since Coursera is home to so many different types of courses, it may be overwhelming to decide what your first online class will be.

Below, check out the most popular Coursera classes, ranked by the number of students enrolled, for some guidance. All enrollment numbers are as of September 2020.

1. Machine Learning, Stanford University | 3.5 million enrolled

Learn about the most effective machine learning techniques and how to implement them. The intro course covers machine learning, data mining, and statistical pattern recognition, as well as a look into how machine learning and AI lead to innovation in Silicon Valley.

2. The Science of Well-Being, Yale University | 2.9 million enrolled

One of Yale's most famous classes is basically a crash course on how to be happier in your life. Topics include misconceptions about happiness, how to overcome our biases, and practical strategies to make you happier.

3. Learning How to Learn, McMaster University and UC San Diego | 2.5 million enrolled

The practice of learning is a class in itself. Take this popular class and you'll be set up with the best learning techniques to tackle and master any topic in the future. It's also available in fully translated versions in Spanish, French, Chinese, and Portuguese.

4. Programming for Everybody, University of Michigan | 1.8 million enrolled

Although programming can sound intimidating, this course assures you there are no significant pre-requisites and uses only simple math. If you have moderate computer experience, you'll be able to make a program from a series of simple instructions in Python.

5. Successful Negotiation, University of Michigan | 898,000+ enrolled

Negotiating is engrained in our everyday lives, from deciding where to eat with your significant other to asking for a few more days to pay rent. And, it's essential to business. You'll learn about the four steps to a successful negotiation so that both parties emerge satisfied.

6. Chinese for Beginners, Peking University | 837,000+ enrolled

Mandarin Chinese is an essential global language to learn. This spoken language class includes basic conversations that you'll be able to use in everyday life.

7. Neural Networks and Deep Learning, deeplearning.ai | 811,000+ enrolled

Deep learning is a highly sought after skill in the job market right now. Part of the larger Deep Learning Specialization, this is an opportunity to understand the foundations of a skill that's been called a "superpower."

8. Algorithms, Part 1, Princeton University | 725,000+ enrolled

If you want to be a serious programmer, you can learn elementary data structures, sorting, searching algorithms, and graph- and string-processing algorithms. This course doesn't offer a certificate, so all the features are free.

9. Bitcoin and Cryptocurrency Technologies, Princeton University | 438,000+ enrolled

We've all heard the craze around bitcoin, but confusion and misconceptions run rampant. Basics like "how does bitcoin work" and "how secure are your bitcoins" are among the many lessons you'll learn.

More online classes:

• 54 free online courses from the best colleges in the US — including Princeton, Harvard, and Yale
• 6 places to take free and affordable classes online, on everything from programming to photography
• Skillshare is giving away 2 months of free access to thousands of online classes — I took a class with one of my favorite authors and loved it
• Coursera offers a free online class called 'Learning How to Learn' that gives you the tools to master any topic
• GoSkills offers affordable online classes that teach many of the business skills employers want