• It is a Distributed, Immutable, Journal log of transactions of value.
  • It's not a Chain, but a Tree, starting from a Genesis Block, branching as Chains. New Blocks are only added to the most computationally complicated (“longest”) valid Chain.
    • Single block forks can occur when two blocks were received within seconds.
      • In which case, new blocks are added onto the first received.
      • Shorter chains then have all their transactions requeued, to end up on the main Chain.
  • Blockchains is a single store not integration store.