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HTLC

Definition

Hash Time-Locked Contract — a smart contract enabling conditional payments: the recipient must provide a cryptographic proof within a time limit or the payment returns to the sender. The building block of Lightning Network routing.

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Difficulty
Advanced
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Category
Technology & Protocol
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See Also
8 related

◆ Key Takeaways

1

Hash Time-Locked Contract — a smart contract enabling conditional payments: the recipient must provide a cryptographic proof within a time limit or the payment returns to the sender.

2

The building block of Lightning Network routing.

Why It Matters

This technical concept underpins how blockchains actually work. Developers, validators, and advanced users need this knowledge to build, secure, and optimize blockchain systems.

Related Terms in Technology & Protocol

Proof of Work
A consensus mechanism where miners compete to solve complex mathematical puzzles to validate transactions and create blocks. Requires significant computational power and energy. Used by Bitcoin and provides the strongest known security guarantees.
Proof of Stake
A consensus mechanism where validators stake cryptocurrency as collateral to participate in block creation. Selected proportionally to stake amount. More energy-efficient than PoW. Used by Ethereum since The Merge (2022).
Delegated Proof of Stake
A PoS variant where token holders vote for a limited number of delegates who validate transactions. Offers faster consensus with fewer validators. Used by EOS, Tron, and other chains prioritizing throughput.
Proof of Authority
A consensus mechanism where pre-approved validators with known identities produce blocks. Sacrifices decentralization for speed and efficiency. Used in private blockchains and some testnets.
Proof of History
Solana's innovation creating a verifiable ordering of events using cryptographic timestamps before consensus. Enables parallel transaction processing and sub-second block times by establishing time without waiting for network agreement.
Proof of Space
A consensus mechanism where participants prove they have allocated disk storage space. More energy-efficient than PoW. Used by Chia and Filecoin for storage-based consensus.
Proof of Burn
A mechanism where tokens are permanently destroyed to earn the right to mine or validate. Demonstrates commitment by sacrificing value. Used as an alternative to PoW's energy expenditure.
Consensus Mechanism
The method by which blockchain nodes agree on the valid state of the ledger. Solves the Byzantine Generals Problem. Major types: Proof of Work, Proof of Stake, and their variants.

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