BASH, which stands for "Bourne Again SHell," is a command processor that typically runs in a text window where the user types commands that cause actions. It is a widely used Unix shell and command language, providing a command-line interface (CLI) for interacting with the operating system. BASH is the default shell for many Linux distributions and is available on various Unix-based systems.
For the Security+ exam, understanding BASH is relevant in the context of Linux and Unix system administration, scripting, and security. The Windows equivalent of BASH is PowerShell.