Peercoin is a cryptocurrency which introduced the proof-of-stake model to the cryptocurrency market. Since its release others have used proof-of-stake model, sometimes almost directly from Peercoin's code, to make their own POS cryptocurrency. Peercoins are created by what they call "minting." The rate of profit is 1% annually.
In Februsary 2018, 1 PPC was valued at about $3.09