Comment by Pete_D

The terminal can optionally catch some characters and convert them to signals. By default, ^C sends SIGINT, ^\ sends SIGQUIT, and ^Z sends SIGTSTP. Programs can disable that for their own purposes (stty -isig) and you can rebind them to other characters if you want (stty intr, stty quit, stty susp) but I don't know why anyone would these days.