Bitcoin cash split

On August 1, 2017, Bitcoin Cash (BCH) split from Bitcoin via a deliberate hard fork. Block 478,558 (2017-08-01, ~13:16 UTC) is the last block common to both chains; BCH's first divergent block followed at height 478,559 under different rules (an 8 MB block size limit, no SegWit). Anyone holding BTC at the split height held equal BCH on the new chain. The split was the culmination of the multi-year "block size war" over whether to scale by raising base-layer block size or by SegWit-plus-layers.

Nuance: BCH implemented replay protection and its own difficulty adjustment, making it a clean persistent split rather than a contentious same-rules fork. Market pricing since the split has kept BCH a small fraction of BTC's value — a data point debaters use about which chain the economy treated as "Bitcoin," though "the market decided" is an interpretation, not a protocol fact.

Common misstatements:

• "Bitcoin split in half in 2017." — A new chain split off; the original chain's rules, history, and ticker continuity were unaffected.
• "BCH is the real Bitcoin per the whitepaper." — A position, not a fact; the fact is which chain retained the overwhelming majority of hashrate, nodes, and market value.
• Confusing the BCH fork (August 1) with SegWit activation (August 24) — separate events three weeks apart.