Beowulf Cluster, Beowulf-style Cluster, Beowulf Architecture

A cluster comprised of multiple consumer-grade computers, like common rack-mount servers, tower desktops, or even at some points in history, gaming console systems, all networked together over an interconnect and capable of pooling their computational power together on one task. Before the mid-1990s, it was common for parallel computing and HPC to require an entirely specialized computer architecture designed for that dedicated purpose, but with the advent of faster networks and beginnings of the MPI standard around that time, the development of specialized architectures fell out of favor versus just wiring together large numbers of commodity-grade computers. Most modern supercomputers now follow the Beowulf architecture—they are comprised of multiple standard server-type computers all networked together over an extremely fast interconnect, with some kind of fast storage attached as well. So, scaling out is as easy as buying more of the same type of consumer-grade compute node servers as you already have, while scaling up would look like upgrading the CPUs or RAM, or maybe adding some GPUs, to the servers you already have.