Bitcoin forksNonconsensus rule changesHard forksSoft forksDifferences between hard and soft forksTransaction replayReplay protectionUpgrade mechanismsUsing coinbase signaling—BIP16Using incremented block version number signaling—BIP34, 66, and 65Using block version bits signaling—BIP9Using BIP9 to deploy relative lock timeUsing BIP9 to deploy segwitUser-activated soft forksRecapExercisesWarm upDig inSummary