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Peer-to-peer networks

It wasn't long before personal computers were connected together in networks, where their collective power could be utilized. Computations performed by powerful mainframes could now be spread across many personal computers in a method known as distributed computing.

With the arrival of the internet on April 30, 1993, personal computers were able to connect to other personal computers anywhere in the world. Early peer-to-peer (P2P) networks allowed users to share files with each other over the entire world. The following diagram shows such a network:

SETI@home is a distributed computing project designed to analyze radio signals in order to look for signs of extraterrestrial intelligence. SETI@home depends on volunteers who donate their internet-connected computer's downtime to the distributed network. With this architecture, SETI@home is the largest supercomputer in the world.

P2P networks became notorious for digital piracy. P2P applications such as Napster allowed users to share songs over the internet with others, bypassing copyright laws. Despite this, P2P networks continued to flourish. Blockchain, the technology behind Bitcoin, operates on a P2P network of computers that each hold an identical copy of a ledger of transactions.