First let me give you an example

LETS TALK TMUX

From Acrolinux

Install tmux

sudo apt install tmux

brew install tmux

Benefit of using tmux

tmux

WHAT DO WE DO NEXT?

tmux

C-d writes an EOF (end of file) to the stdin, which closes the shell

Understanding note

When you see C-* C = ctrl, * = any key. So the previous example is Control + d.