Peercoin (Peercoin, historically known as PPCoin, ticker PPC) is an alternative cryptocurrency that has taken a special place in the history of the industry. Its main merit is that it was one of the first to introduce and test in practice the Proof-of-Stake (PoS) mechanism in combination with the classic Proof-of-Work. The project was created by developers known as Sunny King and Scott Nadal.

The idea of the hybrid model was to reduce the network's dependence on energy-intensive mining over time. In pure PoW systems security is provided by computing power, which requires significant electricity costs. The Proof-of-Stake mechanism allows participants to confirm transactions based on the number of coins they own and hold in the network, which makes the system more economical.

Peercoin had a noticeable impact on the further development of cryptocurrencies: the Proof-of-Stake concept, first tested in this project, became the basis of many modern blockchains. Therefore, studying Peercoin is important for understanding the evolution of consensus algorithms and the search for more sustainable models of network protection.