If you're using Linux, BSD, or another *nix operating system, I'll assume you already know about the Terminal; you probably even know how to get Python up and running already. For those who aren't familiar with opening Terminal or the command prompt (same thing, different name on different operating systems), the following sections explain how to do it.
The interactive Python interpreter is sometimes referred to as the Python shell, Python prompt, Python terminal, or Python command line. They all mean the same thing—a special, text-based interface that allows for Read-Evaluate-Print Loop (REPL) interaction with Python.