What is the Command Line?
The Command Line Interface (CLI) is a means of interacting with your computer via text commands. While it seems that the CLI is archaic compared to GUIs (Graphical User Interfaces) it's actually a very powerful method for interacting with files and programs.
The application where you type your commands (and see any results of those commands) is called a shell. There are different types of shells, but the most common is the Bash shell which is what Linux and Mac systems use.
On Macs, Bash shell is accessed via an included application called Terminal.
Windows systems include the limited Command Prompt application, which has nowhere near the power of Bash. Windows also has PowerShell, but the commands are different than what is used in the Bash shell.
Given this, Windows users are going to use a console emulator called Cmder which will allow you to mostly replicate anything you'd do in a Bash shell.
In the following docs, we'll cover Terminal and Cmder in more details.
People use different terms when referring to a Command Line Interface - bash, shell, terminal, command line, etc. For the sake of consistency we'll use the term Command Line or CL for short.
Unless otherwise specified, when referring to Command Line we mean Terminal on Mac and Cmder on Windows.