The Terminal Without Fear

To work with Docker you type commands into a terminal — a plain text window where you tell the computer what to do. If the word 'terminal' makes you nervous, the next ten minutes will put you completely at ease: you type a command, press Enter, and read the reply. That is it. There is no magic here

The terminal is like texting the computer: you write a short, clear instruction, press send (Enter), and the computer 'replies' on the line below.

terminal: A text window where you type commands to the computer and read its replies. Also called the 'command line' or 'console'.
prompt: The symbol (often $) that says 'I am ready, type a command'. It appears whenever the terminal is waiting for you.
command and arguments: A command starts with a program's name, followed by 'arguments' — extra words that tell it exactly what to do. For example in `docker run hello-world`, the program is docker and the rest are its instructions.