Lightning, Sidechains, Modular DA, and Account Abstraction

What you'll learn

• The Lightning Network: Bitcoin's Scaling Layer
• Sidechains: Independent Chains with Bridges
• Modular Blockchains and Data Availability
• Account Abstraction: ERC-4337 and EIP-7702
• Choosing Between Approaches

Key terms

Lightning Network

A state-channel network on Bitcoin enabling instant, near-zero-fee payments. December 2025: approximately 5,637 BTC capacity (a record), 14,940 nodes, 48,678 channels.

Payment channel

A two-party Lightning channel funded by a single on-chain Bitcoin transaction, allowing unlimited off-chain updates. Closed by either party broadcasting the final state to the blockchain.

Sidechain

An independent blockchain with its own validator set and consensus, connected to a main chain via a bridge. Polygon PoS is the largest example, launched May 2020.

Polygon POL migration

The 1:1 migration from MATIC to POL governance token. Began September 4, 2024.

Modular blockchain

An architecture separating execution, settlement, consensus, and data availability into specialized layers. The dominant paradigm for new chains since 2023.

Celestia (TIA)

The leading modular data-availability layer. Mainnet launched October 31, 2023. Provides cheap blob storage for rollups that prefer not to use Ethereum for DA.

EigenDA

Eigen Layer's data-availability service launched April 2024. Leverages Ethereum validator set through restaking. Used by rollups seeking cheap DA with Ethereum-aligned security.

Avail

A modular data-availability layer launched mainnet July 23, 2024. Originated within Polygon's research before being spun out as an independent project.

Cosmos IBC

The Inter-Blockchain Communication protocol enabling cross-chain transfers between Cosmos SDK chains. Battle-tested across hundreds of connected chains.

Account abstraction (ERC-4337, EIP-7702)

ERC-4337 (live March 2023) introduced smart accounts; 26-40 million accounts and 170 million+ UserOperations to date. EIP-7702 (shipped Pectra, May 7, 2025) lets existing EOAs delegate to smart-contract logic; 14 million EOAs have signed authorizations.