Chain Reorganization

The term "blockchain reorganization" is used to refer to the situation where a client discovers a new difficultywise-longest well-formed blockchain which excludes one or more blocks that the client previously thought were part of the difficultywise-longest well-formed blockchain. These excluded blocks become orphans.

Chain reorganization is a client-local phenomenon; the entire bitcoin network doesn't "reorganize" simultaneously.

See also

• Irreversible Transactions