The Ethereum Byzantium hard fork will happen at block 4,370,000 which will occur at approximately 6 UTC October 15, 2017. The first part of a larger, multi-part upgrade, the so-called “Byzantium” code will make the blockchain lighter and faster, paving the way for better decentralized applications (dapps), while also enhancing network privacy.

Track Byzantium: https://fork.codetract.io/