The need to accommodate an increasing count of transactions per second contributed to a push by some in the community to create a hard fork to increase the block size limit.This push came to a head in July 2017 when some members of the bitcoin community including Roger Ver felt that adopting BIP 91 without increasing the block-size limit favored people who wanted to treat bitcoin as a digital investment rather than as a transactional currency.Bitcoin Cash supporters, compared to Bitcoin, were more committed to a medium of exchange function. This push by some to increase the block size met a resistance. Since its inception up to July 2017, Bitcoin users had maintained a common set of rules for the cryptocurrency.Eventually, a group of bitcoin activists, investors, entrepreneurs, developersand largely China-based miners were unhappy with Bitcoin's proposed SegWit improvement plans meant to increase capacity and pushed forward alternative plans for a split which created Bitcoin Cash. Segwit controversially would later enable second layer solutions on bitcoin such as the Lightning Network, and this controversy led to the split that created Bitcoin Cash.[14] The proposed split included a plan to increase the number of transactions its ledger can process by increasing the block size limit to eight megabytes.
In June 2017, hardware manufacturer Bitmain, described the would-be hard fork with the increased block size as a "contingency plan", should the bitcoin community decide to fork implementing SegWit. The first implementation of the software was proposed under the name Bitcoin ABC at a conference that month. In July 2017, mining pool ViaBTC proposed the name Bitcoin Cash. The change, called a fork, took effect on 1 August 2017. As a result, the bitcoin ledger called the blockchain and the cryptocurrency split in two.
A Hong Kong newspaper likened this to a new version of word processing software saying:
Bitcoin cash is like a new version of Microsoft Word, which generates documents that can no longer be opened via the older versions.
Bitcoin cash is doing a “hard fork” or “effectively a software upgrade”, Kelly said on “Fast Money”. “When you do a software upgrade, everybody usually agrees. But in this particular case, everybody is not agreeing.”
At the time of the software upgrade (also known as a fork) anyone owning bitcoin came into possession of the same number of Bitcoin Cash units. The technical difference between Bitcoin Cash and Bitcoin is that Bitcoin Cash allows larger blocks in its blockchain than Bitcoin which, in theory, allows it to process more transactions per second.Bitcoin Cash was the first of the Bitcoin forks, in which software-development teams modified the original Bitcoin computer code and released coins with “Bitcoin" in their names, with "the goal of creating money out of thin air".In relation to Bitcoin it is characterized variously as a spin-off,a strand, a product of a hard fork, an offshoot, a clone,a second version or an altcoin. On 1 August 2017 Bitcoin Cash began trading at about $240, while bitcoin traded at about $2,700.
A key difference of opinion between Bitcoin Cash and Bitcoin camps was over the running of nodes. Bitcoin supporters wanted to keep blocks small so that nodes could be operated with less resources, while some Bitcoin Cash supporters find it acceptable that (due to large block sizes), nodes might only be run by universities, private companies and nonprofits.
In 2018 Bitcoin Core developer Cory Fields found a bug in the Bitcoin ABC software that would have allowed an attacker to create a block causing a chain split. Fields notified the development team about it, and the bug was fixed.