Facebook

This is possibly the most famous side-hustle story in history, thanks to the 2010 film "The Social Network." In case you missed it, here is a reminder: In 2004, Mark Zuckerberg and four undergraduate buddies created what would become Facebook in his Harvard dorm room. Initially, membership was limited to Harvard students, but it was soon expanded to include students from other colleges and, later, anybody with a valid email address. Zuckerberg dropped out of Harvard in his sophomore year to devote his whole attention to Facebook, but he returned in 2017 to earn an honorary degree.

Facebook may be accessed from any device that has Internet access, including computers, tablets, and smartphones. Users can establish a profile after registering, which includes personal information. They can exchange text, photographs, and multimedia with other users who have consented to be their "friends", depending on the privacy settings, with the general public.