> For the complete documentation index, see [llms.txt](https://docs.valuechain.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.valuechain.xyz/1.-architecture-overview.md).

# 1. Architecture Overview

ValueChain is one network made of several chains. This chapter shows how they fit together; the next four chapters describe each layer in turn.

#### 1.1 Three layers

<figure><img src="https://nkhxy47v6o.sg.larksuite.com/space/api/box/stream/download/asynccode/?code=OTcyOTQxOGYyOGRiODViODJhZTBhMTFhOTVkMjI2NTlfVTVsUFdoR0U5RnByTm9WTzAzblE5eUJXVjlEZVNJM1RfVG9rZW46U1ZXYmJ0YjdDb3ppaVJ4cE8ya2xuU1JXZ0ZjXzE3OTExODc2ODA6MTc5MTE5MTI4MF9WNA&#x26;add_watermark=true&#x26;scene_type=CCM" alt=""><figcaption></figcaption></figure>

*External assets enter through Mirror Protocol. The EVM system chain and the SoDEX appchains share one account system and are secured by the CometBFT host chain.*

<table><thead><tr><th>Layer</th><th width="456.921875">Role</th><th>Chapter</th></tr></thead><tbody><tr><td>Host chain</td><td>Consensus and shared security for every chain in the network (CometBFT, single-slot finality).</td><td>5</td></tr><tr><td>EVM system chain</td><td>Unified accounts, settlement and general-purpose smart contracts; fully compatible with Ethereum tooling.</td><td>6</td></tr><tr><td>Application chains</td><td>One high-performance, deterministic application per chain. The first two run SoDEX Spot and SoDEX Perpetuals.</td><td>7</td></tr><tr><td>Mirror Protocol</td><td>Brings external assets onto ValueChain and sends them back.</td><td>8</td></tr></tbody></table>

#### 1.2 One shared ledger, many subchains

The EVM system chain and the appchains run as **subchains** of the host chain. Each subchain is **logically independent**: it has its own state, its own transactions and its own execution rules. The data of all subchains is **stored together within host-chain blocks**. This lets the host chain carry fast, reliable message-passing channels between subchains, so interoperability between them is instant and needs no external bridge.