This is an advanced course on the digital economy. Our two main goals are (a) to understand how people and companies interact in digital markets and (b) to understand how digital markets should be designed and regulated. The course uses a combination of theoretical modeling and empirical evidence in order to achieve those goals. We analyze some key features that are prevalent in digital markets, including such as network effects, two-sided markets, search and matching, reputation systems, and the use of data. We also zoom in on individual markets, such as media platforms, the gig economy, and artificial intelligence.