Multipath payments split one logical payment across several HTLC paths that share a payment secret/hash scheme so the receiver can reassemble atomically.
Why this matters
Large payments often cannot fit through one channel’s available balance. MPP raises success rates and effective capacity without opening enormous channels.
Analogy
Moving a couch through a city: sometimes three smaller vans beat one truck that does not fit the alley.
Loading diagram…
Worked mental model
Re-read the diagrams in this lesson once out loud in plain language. If you cannot explain the flow to a friend without jargon, pause and revisit Mastering Bitcoin / Mastering Lightning chapters linked in Resources. Chapter references are intentional, not decorative.
Hands-on habit
Every protocol idea should be paired with one local experiment:
- Reproduce the happy path on regtest (or Polar for Lightning)
- Break it on purpose (wrong fee, expired invoice, offline peer)
- Write down what error you saw and which layer produced it (wallet, node, mempool, peer)
That habit turns reading into builder instinct.
Glossary check
Pick three terms from this lesson and define them in one sentence each without opening notes. Weak definitions mean the lesson is not finished yet.
Resource order
Use Resources in order: narrative book chapter first, then BIP/BOLT for precision, then implementation docs for commands. Jumping straight to RPC flags without the mental model creates brittle knowledge.
Next steps
Failure handling: what to do when paths fail and retries are required.