Distributed computation
Some programs may be broken down into separate sub-programs that execute the same whether they run one after the other or in parallel. The subprograms can then be processed by a number of computers at once, in order to share the load. Such systems are sometimes peer-to-peer, but are rarely decentralized. They are usually organized in a hub and spoke manner, with the hub coordinating all work and communications. The hub is thus an authority. Computing resources on spokes are often contributed to a communal project in lieu of being wasted. What makes this peer to peer is that it resembles Napster in making use of otherwise stranded resources. See dark matter.
