“A ROBOT SWARM is a self-organizing multi-robot system characterized by high redundancy. Robots’ sensing and communication capabilities are local and robots do not have access to global information. The collective behavior of the robot swarm emerges from the interactions of each individual robot with its peers and with the environment. Typically, a robot swarm is composed of homogeneous robots, although some examples of heterogeneous robot swarms do exist.”
http://www.scholarpedia.org/article/Swarm_robotics