Bitcoin Transaction Locktime
Web3 / blockchain technology
Locktime is a parameter in Bitcoin transactions that specifies the earliest time or block height at which a transaction becomes valid and can be included in the blockchain. It can be set as either a Unix timestamp (seconds since January 1, 1970) or a block height number, and the network interprets it based on whether the value is below or above a specific threshold. If locktime is set to a future time, nodes will reject the transaction until that condition is met, allowing parties to pre-sign transactions that activate only at predetermined times or blocks. This feature enables conditional payments and time-locked contracts without requiring more complex smart contract functionality.
Example
The Lightning Network uses locktime extensively in payment channels, where transactions are pre-signed with future locktimes to ensure that channel participants can recover their funds if the counterparty becomes unresponsive or acts maliciously.
Why It Matters
Locktime enables atomic swaps, payment channels, and time-based financial agreements on Bitcoin without additional layers. It's essential for building scalable solutions and protecting users in multi-party transactions where timing certainty is critical.
Definition maintained by Cointegrity. See our editorial policy for review standards on regulatory and compliance terms.
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