motion compensation

I have utterly no idea what motion compensation is. Can anyone explain it to me, and it's positives and negatives? thanks 

The Motion compensation option is specifically for portable devices. This adds logic to the application so that as a person playing your game moves the motion of the device screen is taken into account. Turning this option on though will increase processing time slightly. Again it’s a setting that will be turned on or off depending on the type of game your creating.
The Motion compensation option is specifically for portable devices...