Terminal, shell, command line.
The terminal, or command line, is a way to interact with computers, by entering text commands and viewing the response. These commands can be used for general use of your computer, or to connect to remote servers to configure them or for certain operations.
Learn the basics of using the terminal, so you can continue learning on your own. This is critical knowledge for using git or installing and using developer tools later on.
Disambiguation
Command Line/Command Line Interface (CLI)
The place where you run commands.
Terminal
A system's text input/output environment, or an attached terminal window.
Console
Originally a device with terminal access.
Shell
The terminal environment. Bash (aka Bourne Again Shell) is a common linux shell.
Command Prompt
Line where you enter commands. Can be customized to show info like user name and current directory.
Basic commands
ls - list content
mv - move
cd - change directory
cat - print file contents
GNU Readline
The library for handling command entry.