This is a collective motion simulation based on the so-called Vicsek model (Wikipedia article). The particles represent for example fish, locusts, or birds. They move with fixed velocity (self-propelled) and adjust their movement direction to their neighbours. This is similar to a ferromagnet where microscopic magnets adjust their spins but don't change position. As the magnet, the moving system can show a "phase transition" from unordered to swarm-like, depending on the strength of the random perturbations. Interestingly a similar effect of organized motion can be observed if particles repel each other ( Grossman, Aranson and Jacob 2008). In our study, we examined a model that combines alignment and repulsion of particles. Such imperfect alignment, surprisingly, can improve collective motion. As illustrated below in Figure (a) - (c), where the angle alpha describes the deviation of particles from perfect alignment with its neighbours, imperfect alignment facilitates the formation of larger groups of particles that share a similar direction. Perfect alignment leads to small groups that can each move in a different direction.