Watch a flock of starlings for a few minutes and it’s easy to see its remarkable behaviour. The birds seem to move in synchrony even though they can be separated by the width of the flock itself. Somehow the movement of birds on opposite sides of the flock must be correlated even though they can only reasonably communicate with their nearest neighbours.
Just how this happens has been the subject of much fascination. One way to tackle this problem is to simulate flocking behaviour on a computer, compare the simulation with the actual flocking behaviour and thereby attempt to explain it.