---
title: "Bitcoin Layer 2s Explained: State Channels, Sidechains and Rollups"
description: "An overview of how the Lightning Network, sidechains, and emerging rollup architectures attempt to scale the Bitcoin network by moving transaction execution off the primary blockchain."
url: https://basisdesk.news/learn/bitcoin-layer-2s-explained
published: 2026-10-29T08:30:31.686Z
modified: 2026-10-29T08:30:31.686Z
section: Bitcoin
author: Basis Desk Newsroom (AI-generated, source-verified)
sentiment: neutral
tickers: [BTC, STX]
tags: [Bitcoin, Layer 2, Lightning Network, Sidechains, Rollups, Scaling]
license: Quote with attribution to Basis Desk (basisdesk.news). Not financial advice.
---

# Bitcoin Layer 2s Explained: State Channels, Sidechains and Rollups

An overview of how the Lightning Network, sidechains, and emerging rollup architectures attempt to scale the Bitcoin network by moving transaction execution off the primary blockchain.

## Key points

- Layer 2 networks shift transaction execution off the primary blockchain to improve throughput and reduce fees.
- The Lightning Network uses state channels for peer-to-peer microtransactions without relying on distinct blockchains.
- Sidechains like Liquid and Rootstock operate separate blockchains connected to the main network via federated two-way pegs.
- Emerging rollup architectures aim to mathematically prove offchain execution on the base layer to minimize trust assumptions.

Bitcoin Layer 2 networks are secondary protocols built on top of the foundational Bitcoin blockchain designed to increase transaction throughput, reduce fees, and introduce programmable smart contracts. These systems achieve scale by processing transactions off the main network while relying on the primary blockchain for final settlement and dispute resolution [1].

## The scaling challenge and the layer architecture

The base $BTC network limits the amount of data included in each block to maintain a decentralized network of nodes. A new block is generated roughly every 10 minutes, and the network processes approximately five to seven transactions per second. When demand for block space increases, users must attach higher fees to their transactions to incentivize miners to include them. This dynamic makes the primary blockchain impractical for microtransactions or complex programmable logic.

A **Layer 2** solution shifts the bulk of transaction processing away from this congested base layer, commonly referred to as **Layer 1** [1]. By batching or netting multiple transactions offchain and only recording the final state or cryptographic proofs on the primary blockchain, Layer 2s theoretically allow the network to handle millions of transactions per second. However, moving execution away from the base layer introduces new trust assumptions and security trade-offs. The mechanism used to lock assets on the main chain and issue representative assets on the secondary network—known as a **two-way peg**—is often the central point of vulnerability in these systems [2].

## State channels and the Lightning Network

The Lightning Network is the most widely adopted Layer 2 on Bitcoin, specifically optimized for high-volume, low-latency payments. It operates using a technology called state channels. Two parties open a channel by submitting a funding transaction to the primary blockchain, locking a specific amount of BTC in a multi-signature address [3].

Once the channel is open, the parties can transact an unlimited number of times by exchanging cryptographically signed updates to the distribution of the locked funds. These intermediate transactions occur entirely offchain and are nearly instantaneous. If Alice and Bob open a channel funded with 1 BTC (Alice providing 0.6 BTC and Bob 0.4 BTC), Alice can send Bob 0.1 BTC by signing a new balance state where she owns 0.5 BTC and Bob owns 0.5 BTC. The base blockchain is unaware of this transfer. The channel is only settled on Layer 1 when the parties decide to close it, broadcasting the final balance to the network.

For example, if Alice wants to send funds to Charlie, she does not need a direct channel with him. The Lightning Network uses a routing protocol where Alice can route the payment through Bob, assuming Bob has a channel with Charlie and sufficient liquidity. Bob charges a routing fee, which typically consists of a base fee and a liquidity fee proportional to the payment size. If the base fee is 1 satoshi and the proportional fee is 10 parts per million, a routed payment of 100,000 satoshis will cost Alice 2 satoshis in routing fees. This system requires nodes to remain online to route payments and monitor the blockchain for fraudulent channel closures [3].

## Sidechains: Liquid and Rootstock

Sidechains are independent blockchains that operate in parallel to the main network and are connected via a two-way peg. Unlike state channels, sidechains have their own consensus mechanisms and block generation rules, allowing them to support custom features like smart contracts and faster block times [2].

The Liquid Network is a sidechain designed primarily for institutional users, exchanges, and market makers to facilitate rapid, confidential asset transfers. It relies on a federated model, where a consortium of known entities called functionaries operates the network hardware. To use Liquid, users send BTC to a multisignature address controlled by the federation. The federation then mints an equivalent amount of Liquid Bitcoin (L-BTC) on the sidechain. When users want to return to the main chain, they burn the L-BTC, and the federation releases the locked BTC. The security of the peg relies entirely on trusting that a supermajority of the federation will not collude to steal the locked funds [4].

Rootstock (RSK) is another prominent sidechain, distinguished by its compatibility with Ethereum smart contracts. Rootstock achieves consensus through **merged mining**, allowing traditional Bitcoin miners to secure the Rootstock network simultaneously without expending additional computational power [5]. Like Liquid, Rootstock relies on a federated peg—managed by a group known as the Powpeg—to handle the transfer of BTC into smart Bitcoin (RBTC). While merged mining aligns the sidechain's security with the base layer's hash rate, the federated peg remains a central point of trust [5].

## Execution layers and Stacks

Stacks operates as a companion execution layer that introduces complex smart contracts to the ecosystem without altering the base layer's consensus rules. Unlike traditional sidechains that use federated pegs or merged mining, Stacks utilizes a distinct consensus mechanism called Proof of Transfer (PoX) [6].

In the PoX model, Stacks miners do not burn energy to validate blocks. Instead, they bid base layer BTC for the right to mine Stacks blocks and earn rewards in the native STX token. The BTC bid by miners is distributed to STX holders who lock their tokens in a process called stacking. The Stacks network writes cryptographic hashes of its blocks to the primary blockchain, anchoring its transaction history to the base layer. A forthcoming update aims to introduce sBTC, a decentralized, non-custodial two-way peg mechanism designed to allow users to move assets between the layers without relying on a centralized federation [6].

## The shift toward rollups

Inspired by scaling solutions on Ethereum, developers are increasingly exploring rollups for Bitcoin. A rollup executes transactions offchain and submits a compressed summary of the transaction data to the base layer [7]. This approach allows the base layer to verify the correctness of offchain execution. See also: [Layer 2s and Rollups, Explained: How Blockchains Scale](https://basisdesk.news/learn/layer-2-rollups-explained).

Rollups generally fall into two categories: optimistic rollups and zero-knowledge (ZK) rollups. Optimistic rollups assume transactions are valid by default and provide a challenge period during which participants can submit fraud proofs to penalize malicious actors. ZK rollups use complex cryptography to generate validity proofs, guaranteeing the mathematical correctness of transactions without revealing the underlying data [7].

Implementing rollups on the base network is technically challenging because its scripting language lacks the expressivity required to easily verify complex cryptographic proofs. Recent theoretical frameworks, such as BitVM, attempt to bypass these limitations by moving the verification logic offchain and only using the base layer to arbitrate disputes. These architectures aim to create trust-minimized two-way pegs, allowing users to withdraw funds even if the rollup operators become malicious. See also: [Developer Unveils Lichen Design for Trust-Minimized Bitcoin Layer-2 Exits](https://basisdesk.news/news/lichen-bitcoin-layer-2-bitvmx-exit-design).

## Common misconceptions

*   **Layer 2 tokens are altcoins:** While some networks use native tokens for governance or consensus, networks like Lightning and Liquid use versions of BTC directly as their primary asset.
*   **Layer 2s inherit full base layer security:** No current secondary network has the exact security profile of the primary blockchain. State channels require constant monitoring, federated sidechains require trusting a consortium, and rollup implementations remain experimental.
*   **Transactions are completely free:** Layer 2 networks still require fees to compensate node operators, federations, or sequencers for routing, executing, and anchoring transactions, though these fees are fractions of a cent.

## What to watch

The fundamental tension in this sector remains the trade-off between programmability, speed, and the trust assumptions of the peg mechanism. The industry is closely monitoring the implementation of decentralized pegs and dispute resolution systems like BitVM. If developers can successfully verify ZK or fraud proofs natively without requiring forks to the base layer consensus rules, the architecture of Bitcoin scaling will shift rapidly away from trusted federations and toward verifiable cryptography. The regulatory treatment of federated signers and node operators by entities like the SEC or ESMA—specifically regarding custodial definitions—will also heavily influence network design.

## FAQ

**What is a two-way peg?**

A two-way peg is the mechanism that locks assets on the primary blockchain and issues equivalent representative assets on a secondary network, allowing value to move between layers.

**Does the Lightning Network require its own token?**

No, the Lightning Network uses standard BTC to fund channels and settle transactions.

**What is merged mining?**

Merged mining allows traditional miners to secure a secondary blockchain like Rootstock using the same computational power they use for the primary blockchain.

**Are Layer 2 transactions permanently recorded on the main blockchain?**

No, typically only the opening and closing states of channels, or aggregated cryptographic proofs of batches, are recorded on the primary blockchain.

## Sources

1. [Stacks Documentation](https://docs.stacks.co/) — Stacks
2. [Lightning Network Paper](https://lightning.network/lightning-network-paper.pdf) — Lightning Network
3. [Liquid Whitepaper](https://docs.liquid.net/docs/technical-overview) — Blockstream

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Basis Desk Newsroom · AI-generated, source-verified · https://basisdesk.news/about/how-we-use-ai