Graphical user interfaces lowered the barrier to using computers for many people and enabled new applications. However, in software development and system administration, Command Line Interfaces (CLIs) are still widely used. Users input text commands individually in a command line interface, often receiving a text output after each executed command. Terminal User Interfaces (TUIs) are used by interactive programs while operating within a text-based terminal. Think of two-pane file managers or text editors that work over the whole terminal screen. There are several text-based shells that we can use, but the most common and useful to know is Bourne Again SHell, known as Bash. It is the shell commonly associated with Linux since it is installed by default on most Linux distributions, such as Ubuntu or Fedora. Another popular shell is Z shell (Zsh), now the default shell on macOS. While Bash is an excellent choice for scripting thanks to its ubiquity, Zsh is used by developers and sysadmins for its interactivity and configurability. Fish shell is also gaining popularity, being designed to be a user-friendly shell with good defaults. However, it is less compatible with the other mentioned shells. Windows operating system also has its shell called PowerShell. For software developers, sysadmins and data scientists. For anyone who needs to control Linux or BSD systems like personal computers, servers, virtual machines and containers.