Definition
BOLT stands for Basis of Lightning Technology, the set of open specifications that define how Lightning Network implementations interoperate. Maintained collaboratively in a public repository, the BOLTs are the shared rulebook that lets independently written software, such as LND, Core Lightning, Eclair, and LDK, all speak the same protocol and route payments to one another.
What the BOLTs cover
The specifications are numbered and modular. They define the peer-to-peer wire protocol and encryption (BOLT 1 and 8), channel establishment and lifecycle (BOLT 2), the exact on-chain transaction and HTLC output formats (BOLT 3), onion-routed payment packets (BOLT 4), channel closing (BOLT 5), the gossip protocol that builds the routing graph (BOLT 7), and the payment-request format (BOLT 11).
Why specifications matter
Lightning has no central operator. The BOLTs are what make it a network rather than a collection of incompatible wallets. They represent thousands of hours of careful protocol engineering, and they evolve through a feature-bit system that lets nodes negotiate which optional capabilities, like splicing, they both support, preserving backward compatibility as the protocol grows.
The BOLT specifications underpin every Lightning concept, from the BOLT11 invoice a wallet scans to the payment channel that carries the funds.
In Simple Terms
BOLT stands for Basis of Lightning Technology, the set of open specifications that define how Lightning Network implementations interoperate. Maintained collaboratively in a public repository,…