A reverse shell is a type of computer code that allows someone to control a computer from a remote location. It works by creating a connection between two computers. The first computer, called the "client", sends out a special message with code called a "reverse shell". The other computer, called the "server", receives the message and runs the reverse shell code. This allows the person controlling the client computer to make changes to the server computer. They can run programs, change settings, and access files. Because the server computer is running remotely, this person can control the computer without being physically near it.