Bitcoin cash is a fork of the original bitcoin blockchain: It's a new software that has all the history of the old platform, but is made up of eight megabyte "blocks" instead of one megabyte blocks, making it faster. 
If you are not careful, you may accidentally expose your private keys while claiming your BCH. 
When the first block was mined, the price of Bitcoin Cash was trading at roughly $219 on digital currency exchange Kraken. There is a strong correlation between BTC prices and BCH prices. 
BitcoinCash is Bitcoin
There is an online movement which purports that Bitcoin Cash is the true Bitcoin and the vision of Satoshi Nakamoto , the original author of the Bitcoin Whitepaper . Roger Ver is one of the main proponents of this ideology. Many of these people believe there will be a so-called Flippening wherein the value of BCH would exceed BTC's value.