# Farcaster's Structure

**Published by:** [huhyun](https://paragraph.com/@huhyun/)
**Published on:** 2024-10-13
**URL:** https://paragraph.com/@huhyun/farcasters-structure

## Content

Farcaster operates using Hubs as key components for data transmission and storage, bridging communication between compatible blockchains like Optimism and Ethereum. Its architecture consists of three layers: off-chain data, on-chain identity, and applications.Off-Chain Data LayerThe off-chain system is a peer-to-peer network of Hubs that store user data. Most user actions are processed and stored within these Hubs, including:Posting new content.Following other users.Reacting to posts.Updating profile pictures.On-Chain Identity LayerFarcaster’s on-chain system is deployed on the Optimism mainnet to ensure security and data consistency. On-chain actions are kept minimal to reduce costs and optimize performance, and include:Creating new accounts.Paying for data storage.Adding account keys for connected apps.How Farcaster WorksHubs function as distributed, peer-to-peer servers for validating and storing off-chain data. Users can set up their own Hub by installing it on a VPS. Each Hub synchronizes both on-chain data from Ethereum and off-chain data from other Hubs, storing a full copy of Farcaster’s data accessible via APIs. When a validator node is involved, it ensures the integrity of every action within the Hub network. For example, when a user posts a message, it is signed with their account key. The message is then sent to a Hub, where validators verify it through signature checks and property validation. After validation, the message is stored locally, replicated across other Hubs, and synchronized with both the Layer-2 Optimism and Layer-1 Ethereum databases. This structure ensures secure, efficient data management while maintaining decentralized storage and network-wide synchronization.

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