when i type in word and i try to go back and type other things in it just writes over the other letters i think i hit a hotkey to turn it on but don't know the hot key to turn it off so if some one knows the hot key that would really help me out a lot and if any one knows what this is called i would like to know that too because it has happened many times before

ok thx i have been trying to figure that out for a while