Internal Cheating:
External Cheating:
Multiplayer Cheating:
Only the first one actually is about... well... Cheat Codes.
Cheating while playing games with other people, goes into both of the above types, as it involves both internal (design oversights and tweaking settings to do such things as see through walls) and external (programs to alter the game to give an advantage).
And here on the third bullet it goes the way of "Celestial Emporium of Benevolent Knowledge".