(193 PPcoin active nodes as of 2015/12/09) - Source
Peercoin is an experimental, decentralized digital currency that enables instant payments to anyone, anywhere in the world. Peercoin uses peer-to-peer technology to operate with no central authority: managing transactions and issuing money are carried out collectively by the network.
The original Peercoin software by Sunny King was released under the MIT license. Most client software, derived or "from scratch", also use open source licensing.
Peercoin is one of the first successful implementations of a distributed crypto-currency, described in part in 1998 by Wei Dai on the cypherpunks mailing list, and is the first crypto-currency to implement proof-of-stake. Building upon the notion that money is any object, or any sort of record, accepted as payment for goods and services and repayment of debts in a given country or socio-economic context, Peercoin is designed around the idea of using cryptography to control the creation and transfer of money, rather than relying on central authorities.
Getting started See the peercoin.net website for how to get started using Peercoin.