Overview
This article explores Bitcoin Layer-2 solutions and their emerging importance in the cryptocurrency ecosystem.
Key Concepts Explained
What are Bitcoin Layer-2s?
Bitcoin L2s batch transactions and submit the final state to the Bitcoin blockchain, providing users with settlement guarantees comparable to Bitcoin’s security. Unlike Ethereum L2s focused on scaling throughput, Bitcoin L2s enable complex smart contract execution without increasing Bitcoin’s transaction capacity.
Three Main Types:
- State Channels - Payment channels between parties that batch transactions off-chain before final settlement, exemplified by the Lightning Network
- Sidechains - Semi-autonomous networks with their own consensus mechanisms, using two-way bridges for asset transfers
- Rollups - Recent additions bundling up to 10,000 transactions, available in both optimistic and zero-knowledge variants
Featured Layer-2 Projects
Stacks
Uses Proof of Transfer consensus combining Proof of Stake and Proof of Burn.
Rootstock
EVM-compatible sidechain leveraging Bitcoin’s mining power.
Merlin
ZK rollup supporting Bitcoin wallets and EVM compatibility.
SatoshiVM
Zero-knowledge execution layer using Bitcoin as native gas token.
BOB
First Bitcoin L2 combining EVM compatibility with Rust smart contracts.