A swarm is a collective group of self-propelled entities that move together. Swarm robotics uses large numbers of simple robots that coordinate together without a centralized control through local interactions. Swarm intelligence is an artificial intelligence technique inspired by swarms in nature, using algorithms like ant colony optimization and flocking to achieve collective behaviors from decentralized and self-organized systems. These algorithms were developed to help solve optimization problems. While swarms exhibit benefits like adaptability and novelty, they also have disadvantages like being non-optimal, non-controllable and non-predictable. Swarm robotics has applications in industries, medicine, military and space research.