Single Instruction Multiple Data (SIMD)

The SIMD architecture consists

Many (typically simple) processors, with some local memory.
Executing the same instruction in lockstep, on a small piece of data in its local memory, with the instructions issued by the controller processor.
Such architectures are good for applying algorithms which require the same operation on a large array of elements, however, they suffer badly if the problem results in load imbalances as the processors synchronise after every step. This is not usually a problem for data parallel programs.