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Architecture

Linea is a permissionless blockchain network composed of three main architectural components:

  • Sequencer
  • Prover
  • Bridge relayer

Current status​

Linea Mainnet is in beta status and the team is working toward:

  • Reducing proving costs
  • Reducing transaction settlement time
  • Achieving full decentralization

The following represents the main components of Linea, and how they interact:

Linea architecture diagram

What is Linea?​

Linea's fast (2s blocks) and low-cost transactions are compressed into batches and submitted to Ethereum for validation. Blockchains that submit their state changes to a finalization layer in this way are classified as layer-2 networks (L2s).

The network consists of several functional components:

  • Blocks: store state and contracts, keep track of addresses and which tokens are allocated to which addresses.
  • Consensus mechanism: many distributed nodes agree on the validity of state changes, such as the movement of tokens from one address to another.
  • Execution environment: the EVM (Ethereum Virtual Machine) where computer programs can be run. The EVM executes smart contracts and computes state transitions.

While this is an oversimplification, it is helpful when discussing the tradeoffs all such networks must make.

Ethereum prioritizes security. Its consensus mechanism is designed to ensure that no one can singlehandedly alter the state of the network. This is a very impressive feat of engineering, but it comes with a tradeoff: it limits the amount of work the execution environment can do, because the consensus mechanism intentionally runs slowly, to keep everything safe.

Linea and other L2s benefit from the security mechanism of Ethereum while optimizing for execution. L2s enable users to move tokens, run programs, deploy contracts, and mint NFTs quickly and cheaply, while relying on Ethereum's consensus to provide final and censorship-resistant verification of the state changes. By sending regular reports of activity on Linea to Ethereum, the network can optimize for execution without being as limited by security.

Submitting the summaries of activity to the finalization layer, the layer-1 (L1), is known as "rolling up": we can say that Linea "rolls up its transactions to Ethereum". Given that Linea relies on Ethereum for its security, people say that it's "built on top of Ethereum": it's a "second-layer network", an L2.

note

Layers are an extendible concept. For example, you can run a private Linea instance that rolls up its transactions to the public Linea, which submits its grouped batches to Ethereum. This creates a layer 3 ( L3, the private Linea instance) submitting to the L2 (the public instance) which rolls up to Ethereum, the L1.

What distinguishes Linea from many other L2s is how the rollup is performed. Linea uses cutting-edge developments in a branch of mathematics and computer science known as zero-knowledge (zk), or zero-knowledge cryptography, to prove to Ethereum that the activity on the Linea network is valid. By allowing Ethereum to verify a zk proof, rather than rechecking every individual transaction, Linea achieves a significant efficiency gain.

Together, these properties make Linea a zkEVM L2 network built on Ethereum.

Linea blue circle

Next steps​