> ## Documentation Index
> Fetch the complete documentation index at: https://docs.train.tech/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction

> A trustless, permissionless cross-chain bridging (swapping) solution.

The **TRAIN** Protocol (**TR**ustless **A**tomic **IN**tents) is a peer-to-peer system for bridging and swapping crypto assets between blockchain networks. The protocol is implemented as a set of persistent, non-upgradable smart contracts deployed to all [supported networks](/protocol/contracts).

* TRAIN is built on top of [HTLC with recoverable secret generation](/protocol/atomic-swaps-secret_gen). This allows two parties—the **User** and the **Solver**—to exchange assets trustlessly across different chains. Users send their **Intents** to Solvers, who fulfill these Intents using Atomic Swaps.
* There are **no third parties or gatekeepers**. The security of the exchange is fully ensured by:
  * The cryptographic protocol (Atomic Swaps)
  * Local verification through a [Light Client](/protocol/dApp) running in the User's browser

<CardGroup cols={3}>
  <Card title="Try TRAIN in Action" icon="square-1" href="https://testnet.train.tech/">
    Experience TRAIN on all major network testnets, including EVM-compatible chains, Starknet, TON, Solana, and Aptos.
  </Card>

  <Card title="Protocol Concepts" icon="square-2" href="/protocol/the-protocol">
    Explore the core protocol concepts: Users, Solvers, Auctions, and Atomic Swaps.
  </Card>

  <Card title="Protocol Spec" icon="square-3" href="/protocol-spec">
    Dive deeper into the protocol specification and detailed protocol design.
  </Card>
</CardGroup>