Concept of controlling terminal in Unix

There is a process group leader - sort of like the head process - that owns the terminal, /dev/tty. A process group can be one or many processes.

The stty command changes and displays terminal settings. If you are actually going to use UNIX seriously consider finding a copy of Stevens 'Advanced Programming in the UNIX Environment'. Terminals have a lot of heavy baggage from the 1970's. You will spot that right away. Most of those odd settings can be ignored except for special things like UNIX system consoles.