From the Wikipedia:
"Peercoin (code: PPC), also known as PPCoin and Peer-to-Peer Coin is the first cryptocurrency based on an implementation of a combined proof-of-stake (PoS)/proof-of-work system (PoW).
Peercoin (PPC) was created by software developer Sunny King (who later developed the cryptocurrency Primecoin) in August 2012. Peercoin was inspired by Bitcoin, and it shares much of the source code and technical implementation of Bitcoin. The Primecoin source code is distributed under the MIT/X11 software license.
As of 30 November 2013, one Peercoin had a value of approximately 8.2 USD, making Peercoin the third largest cryptocurrency with a money supply valued at 171 million USD. Unlike Bitcoin, Namecoin, and Litecoin, Peercoin does not have a hard limit on the number of possible coins, but is designed to eventually attain an annual inflation rate of 1 percent. This feature, along with increased energy efficiency, aim to allow for greater long-term scalability." (https://en.wikipedia.org/wiki/Peercoin)