Every server speaks this
Almost every web server, cloud machine and container runs Linux, and you control it by typing commands into a shell — usually Bash. No mouse, no windows: just text, which makes it fast, scriptable and the same on every machine.
The shell is a conversation: you type a request, the machine answers, and it waits for the next one at the prompt.
Command, options, arguments
whoami pwd ls ls -l /etc echo Hello from the shell uname -a ls --help history
Options can be combined: ls -l -a is the same as ls -la. Long options use two dashes: --all.