Bitcoin cash (BCH), fully known as bitcoin cash, is a new encrypted digital asset launched by viabtc based on bitcoin ABC scheme. On july21,2017, bitcoin bifurcating scheme bip91 has been supported by the whole network computing power. It was agreed to upgrade the isolation witness first and upgrade the block size of the underlying blockchain to 2m within the next six months. However, the "troublemakers" appeared - the mining pool viabtc under the mining giant bitcoin mainland prepared a hard bifurcation system and launched "bitcoin cash" based on the original chain of bitcoin. Project highlights: online capacity expansion - bitcoin cash follows the roadmap of Zhongben Cong to achieve global popularity through online capacity expansion. As a first step, the block size limit has been set to be adjustable and is raised to 8MB by default. Research to allow the block capacity to be significantly increased in the future is ongoing. New transaction signature - the new sighash type provides replay attack protection, improves hardware wallet security, and solves the problem of secondary hash. The new difficulty adjustment algorithm (DAA) - responsive proof of work (POW) difficulty adjustment allows miners to migrate from the old bitcoin chain to the new chain as they wish, while providing protection against excessive fluctuations in computing power. Decentralized development - the software implementation provided by several independent development teams will be safe in the future. Bitcoin cash can resist political and social attacks on protocol development, and no single team or project can control it. Bitcoin ml mailing list is a good platform for cross development team collaboration to achieve agreement change.