GNU Bash is a command-line shell and scripting language that is widely used in many operating systems, particularly those based on Linux. It allows users to interact with the system by typing commands, which the shell then executes. Bash stands for "Bourne Again SHell," a nod to its predecessor, the Bourne Shell. As part of the GNU Project, Bash is free software, meaning users can modify and distribute it. It supports features like command history, job control, and scripting capabilities, making it a powerful tool for both beginners and advanced users in automating tasks and managing system operations.