> For the complete documentation index, see [llms.txt](https://docs.zetrix.com/zetrix-l2-documentation/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.zetrix.com/zetrix-l2-documentation/introduction.md).

# Introduction

## What is Zetrix Layer 2 (Z2)

**Zetrix Layer 2 (Z2)** is an **optimistic rollup** built on top of the Zetrix Layer 1 (L1) blockchain. It processes transactions off-chain in a high-throughput execution environment and periodically commits compressed, cryptographically anchored state to Zetrix L1. Z2 pairs the optimistic model with an **AnyTrust-style Data Availability Committee (DAC)**: transactions are assumed valid by default, the Sequencer orders them and posts an ordered batch to the L1 **Sequencer Inbox**, the DAC attests that the batch data is stored and retrievable, a **Proposer** posts a state **assertion** to the L1 **Rollup** contract, and independent parties (**Watchers**) re-execute and may dispute an incorrect assertion through a **fraud-proof** process during the challenge window.

> \[!IMPORTANT] **Data availability model (AnyTrust).** Normally the batch data is kept **off-chain** and held/attested by the DAC (keeping cost low). **If the committee cannot reach its attestation threshold, the Sequencer falls back to posting the full batch as L1 calldata.** This "AnyTrust with calldata fallback" design (comparable to Arbitrum Nova) means data can never *silently* disappear — the DA trust assumption is therefore weaker/safer than a pure Validium. See [Trust Model](/zetrix-l2-documentation/architecture/trust-model.md#trust-model).

Z2 is **EVM-equivalent**. The canonical block stream is produced by execution nodes under **QBFT** consensus, and a **second, independent EVM re-executes** the batched blocks for cross-client verification. Applications and users interact with Z2 using the same tooling, wallets, and JSON-RPC interfaces they already use for Ethereum-family chains (MetaMask, ethers.js, web3.js, Hardhat, Foundry).

> \[!NOTE] Z2 is currently deployed on **Testnet**. Deployment figures cited in this document (node counts, server counts) reflect the current Testnet topology and are the reference baseline for the Production recommendation in [Production Deployment Recommendation](/zetrix-l2-documentation/network-and-deployment/production-deployment.md#production-deployment-recommendation).

## Why Layer 2 Exists

Every Layer 1 blockchain faces the **scalability trilemma** — the practical difficulty of simultaneously maximizing decentralization, security, and scalability. Committing every transaction directly to L1 imposes hard limits:

| Constraint   | Impact on L1-only execution                                 |
| ------------ | ----------------------------------------------------------- |
| Block space  | Finite per-block throughput; congestion under load          |
| Gas cost     | Fees rise with demand, pricing out high-frequency use cases |
| Latency      | Confirmation bound by L1 block time and finality            |
| State growth | Every full node must store and validate all state           |

Layer 2 addresses these constraints by **moving execution off L1** while **inheriting L1 security** for settlement and dispute resolution. Z2 executes and orders transactions independently, compresses them into batches, and posts a compact **commitment** to Zetrix L1 (the L1 inbox) while the full transaction data is held by the **Data Availability Committee (DAC)**. This yields orders-of-magnitude higher throughput and lower per-transaction cost while preserving a credible path to L1-enforced correctness via fraud proofs.

## Goals

* **Scalability** — Deliver high transaction throughput and low latency well beyond native L1 capacity.
* **Security inheritance** — Anchor final settlement and dispute resolution to Zetrix L1.
* **EVM compatibility** — Support standard Ethereum tooling, wallets, and smart contracts with minimal friction.
* **Verifiability** — Allow any independent party to re-execute and challenge state transitions.
* **Operational robustness** — Provide high availability, monitoring, and disaster recovery suitable for production.
* **Interoperability** — Bridge native ZETRIX and ZTP20 assets between L1 and L2.

## Benefits

| Stakeholder           | Benefit                                                                     |
| --------------------- | --------------------------------------------------------------------------- |
| End users             | Fast, low-cost transactions; familiar wallet experience                     |
| Developers            | EVM tooling compatibility; standard RPC; smart-contract portability         |
| Enterprises           | Predictable fees, high throughput, auditable settlement to L1               |
| Validators / Watchers | Ability to independently verify and challenge state; open participation     |
| Ecosystem             | Bridged liquidity between L1 and L2; extensible via MCP and relayer tooling |

***

[Index](/zetrix-l2-documentation/readme.md) · [Overall Architecture →](/zetrix-l2-documentation/architecture/overall-architecture.md)