Bitcoin Cash (BCH), was created on the 1st of August, as a result of a Bitcoin network split, otherwise known as a "hard fork." The reason for this fork was the fact that one of the mining pools, "ViaBTC," effectively ignored the original consensus rule that limited the size of blocks to 1MB, and mined a 1.9MB block. This block did not fit in standard Bitcoin rules, so it automatically produced a hard fork, that split the Bitcoin blockchain and causing an entirely new cryptocurrency to appear.
All wallets containing any amount of Bitcoin during the network split automatically received the same number of BCH that they held in BTC. This new cryptocurrency introduced some changes to the network protocol, in opposition to how Bitcoin functions. The changes reflected the fundamental difference in viewpoints of how the Bitcoin scalability issue should be resolved. For example, Bitcoin Cash makes it possible to mine blocks of up to 8MB that fit significantly more transactions in comparison to the 1MB limited blocks of Bitcoin.
Because this hard fork was planned, the team at BCH had enough time to implement other security features which minimized the loss of value and enabled both cryptocurrencies to co-exist.
Official Website: https://www.bitcoincash.org