Tmux is a terminal multiplexer that allows users to manage multiple terminal sessions from a single window. It enables users to split their terminal into multiple panes, run different commands in each pane, and easily switch between them. This is particularly useful for developers and system administrators who need to monitor various processes simultaneously. With Tmux, sessions can be detached and reattached, meaning users can leave their work and return later without losing their progress. It also supports session sharing, allowing multiple users to collaborate in real-time. Overall, Tmux enhances productivity by streamlining terminal workflows.