Bash (Bourne Again SHell) is the default command-line shell on most Linux distributions and macOS, combining the power of the original Bourne shell with modern scripting features. Understanding Bash is essential for system administration, automation, DevOps workflows, and efficient file and process management. While many know basic commands like ls and cd, Bash's true power lies in its scripting capabilities, parameter expansion, process substitution, and text processing tools—features that turn repetitive manual tasks into elegant one-liners. The key mental model: everything in Bash is text, which means pipes, redirection, and command substitution form the backbone of composable, reusable solutions.