peer-to-peer

The term peer-to-peer is a relatively recent addition to the English language, being little more than a half-century old. In its earliest known uses from the 1960s, it referred to something that occurs directly between human peers, people who are similar in age, grade, or status. It can still be found in this use in phrases such as "peer-to-peer tutoring." With the emergence of computer networking, peer-to-peer began to be used in reference to a system of computers that are able to communicate directly with one another without the mediation of a centralized server. Since the turn of the 21st century, peer-to-peer lending—the borrowing and lending of money through online services—has become increasingly common. You might also encounter peer-to-peer in the techy abbreviated form P2P, as in "P2P networking."