What is Bitcoin XT?
Bitcoin XT was a fork from Bitcoin Core. Proposed in BIP 101 and launched in August 2015, the split from the Bitcoin community was due to disagreements on rule changes with some of Bitcoin Core’s senior developers. At the heart of the proposal was increasing block size limits from 1MB to 8MB to allow the network to process transactions more efficiently. Bitcoin XT’s split revealed divisions in the community on the question of block sizes, eventually resulting in Bitcoin Classic’s softer 2MB block size proposal (this also failed) and Bitcoin’s hard fork, Bitcoin Cash.
Bitcoin XT managed to attract some miners initially but ultimately failed and had declined to irrelevancy by 2017. Other proposals to increase block sizes such as SegWit2 also failed to reach developer consensus.