There are many possible reasons to couple lasers: coupled lasers can produce high output powers while maintaining good beam quality, they can be used for secure communication and their behaviour can be of interest for fundamental research. Furthermore, coupled lasers can be used for neuro-inspired information processing approaches like reservoir computing. In this talk, we will give an overview over existing coupling schemes and their applications and discuss their relation to an experiment that we plan to realize in the photonics laboratory: the diffractive coupling of an array of vertical-cavity surface-emitting lasers.