tmux (Terminal Multiplexer) is a modern terminal multiplexer that allows you to manage multiple terminal sessions within a single window. With tmux, you can split windows into panes, detach from sessions, and resume them later, making it ideal for long-running processes and remote work.
screen is a terminal multiplexer that predates tmux but offers similar functionality. It allows you to run multiple terminal sessions in a single window, detach and reattach sessions, and manage background tasks. While screen is older, it remains popular for its simplicity and reliability.