A massively parallel computer is a distributed memory computer system which consists of many individual nodes, each of which is essentially an independent computer in itself, and in turn consists of at least one processor, its own memory, and a link to the network that connects all the nodes together. Nodes communicate by passing messages, using standards such as MPI. Nearly all supercomputers as of 2005 are massively parallel, with the largest having tens of thousands of CPUs. The cumulative output of the many constituent CPUs can result in large total peak FLOPS (FLoating point Operations Per Second) numbers. The true amount of computation accomplished depends in the nature of the computational task and its implementation. Some problems are more intrinsically able to be separated into parallel computational tasks than others. When problems depend on sequential stages of computation, some processors must remain idle while waiting for the result of calculations from other processors, resulting in less efficient performance. The efficient implementation of computational tasks on parallel computers is an active area of research. See also Parallel computing.
In life science and medical diagnostics, massively parallel chemical reactions are used to reduce the time and cost of an analysis or synthesis procedure, often to provide ultra-high throughput. For example, in ultra-high-throughput DNA sequencing as introduced in August 2005 there may be 500,000 sequencing-by-synthesis operations occurring in parallel.