Skip to content
ENFR

GlossaryLayers and protocols

Layer 2

Also · L2 · Second layer · Off-chain

A Bitcoin layer 2 is a system built on top of the blockchain to make payments fast, cheap or private, while keeping funds anchored in Bitcoin and an exit back to it.

Bitcoin’s base layer is slow and expensive on purpose. It is built for final settlement that anyone can verify, not for buying coffee. A layer 2 moves the frequent interactions off the chain and returns to it only to open, close or settle disputes. Lightning is the reference example. Ark, Spark, statechains and rollups follow the same logic with different trade-offs.

The term is used loosely. In the strict sense, a layer 2 lets you recover your funds on Bitcoin without anyone’s permission. A federated sidechain or an e-cash mint does not, which is why our map sorts networks by the trust they require rather than by the label they claim. Every layer above Bitcoin is a bet on which compromise users will accept.

In French · Layer 2

Related terms

Maps

Definition reviewed on October 22, 2026

Read on Off-Chain Media
20 min read

What Is the Lightning Network? Bitcoin's Payment Layer Explained

The Lightning Network is Bitcoin's payment layer, enabling instant, low-cost transactions without compromising decentralization. Discover why it exists, how it solves Bitcoin's scaling limits, and whether it is a viable long-term solution or just an intermediate step in Bitcoin's evolving monetary infrastructure.

15 min read

What is the Ark protocol? The missing piece to make Bitcoin a scalable everyday currency

Bitcoin is often described as a store of value, a form of “digital gold” meant to be held rather than spent. Yet, to function as a true monetary system, it must also enable payments that are fast, simple, and accessible. While solutions like the Lightning Network have significantly improved this aspect, they still introduce a level of complexity that limits adoption. It is in this context that the Ark protocol emerges.

20 min read

What is Spark? The Bitcoin Layer 2 behind the new wave of self-custodial wallets

Spark is a Bitcoin Layer 2 based on statechains and shared signing. It gives wallets a way to offer a Lightning-like payment experience without taking direct custody, but its self-custody guarantees are weaker than holding bitcoin directly on L1.