When you open a terminal window and type commands into the command line or prompt, you are working in a shell. These terms are often used interchangeably, but they are distinct. - **Shell**: the software that executes commands - **Terminal window**: the window that opens when you open the shell. It is a representation of a physical [teletype terminal](https://www.howtogeek.com/428174/what-is-a-tty-on-linux-and-how-to-use-the-tty-command/). - **Command line**: where you type instructions. - **Command**: the input provided by the user. ## Related terms - **Prompt**: synonym for command line. - **Command line interface (CLI)**: common acronym used to describe a shell or API that is executed in a shell. - **Windows Command Prompt**: the shell distributed with Windows, often referred to as cmd. - **[[Bash]]**: the shell distributed with Mac and Linux.