Parity

Popular node software for Ethereum include Go Ethereum, Ethereum C++, and Parity. Parity also supports two other consensus protocols, other than Ethereum's PoW, which are specifically designed for permissioned blockchains. These consensus protocols are Aura and Tendermint. Many Ethereum developers use parity compared to Quorum when they don't need the extra features provided by Quorum. 

As parity doesn't provide any unique features compared to Quorum, we will be skipping parity in this book. But, once you finish this book, you will find it really easy to grasp parity's concepts and will be able to build something using it too.