Historical retrospective · Bitcoin
BIP 65 added a consensus-enforced absolute time lock
BIP 65 redefined the OP_CHECKLOCKTIMEVERIFY opcode so scripts could require a transaction to wait until a specified block height or time.
Time locks enabled more expressive spending conditions while retaining Bitcoin’s existing transaction-validation model.
The change became a building block for payment channels and other constructions that depend on funds becoming spendable only after a condition is met.
Programmable spending conditions expand design options, but complex scripts require careful review and compatible wallet support.
Primary source
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