Wraparound is the name of the inversion that happens when the limits of a finite modulo system are broken. For example, if you have a 16-bit unsigned counter which increments, when it reaches 65535 it will be 'incremented' to 0 (with a carry). In the arcade game Asteroids, when you move your ship off the top of the screen it reappears on the bottom. Pac-man has wraparound through the special tunnels on the left and right of the screen. If you were to keep travelling East from a point on the Earth, eventually you would end up just to the West of where you started, that's a kind of wraparound too (similar to incrementing a longitude counter which can only take values of -180 degrees to 180 degrees, modulo 360 degrees).