Metal is an open-source platform for launching decentralized applications and enterprise blockchain deployments in one interoperable, highly scalable ecosystem. At its core Metal Blockchain is a fork of the highly successful Avalanche project.
Metal Blockchain improves upon the initial work of Avalanche by adding a fourth subchain (A-Chain) to offer a layer for payments and decentralized finance: Proton Blockchain (based on EOSIO protocol). Proton offers feeless transactions to end users.
Additionally, Metal introduces Web Authentication (WebAuthn) support for the Ethereum Virtual Machine (EVM) or C-Chain.
Metal features 4 built-in blockchains: Proton Chain (A-Chain), Exchange Chain (X-Chain), Platform Chain (P-Chain), and Contract Chain (C-Chain). All 4 blockchains are validated and secured by all Metal validators which is also referred as the Primary Network. The Primary Network is a special subnet, and all members of all custom Subnets must also be a member of the Primary Network by staking at least 2,000 METAL.
Proton Chain (A-Chain)
The A-Chain is a new Virtual Machine being developed to provide compatibility with EOSIO based chains, in this case the A-Chain will be an implementation of the Proton chain. For more information about Proton, click here.
Contract Chain (C-Chain)
The C-Chain allows for the creation smart contracts using the C-Chain API.
The C-Chain is an instance of the Ethereum Virtual Machine.
Platform Chain (P-Chain)
The P-Chain is the metadata blockchain on Metal and coordinates validators, keeps track of active Subnets, and enables the creation of new Subnets. The P-Chain implements the Snowman consensus protocol.
The P-Chain API allows clients to create Subnets, add validators to Subnets, and create blockchains.
Exchange Chain (X-Chain)
The X-Chain acts as a decentralized platform for creating and trading digital smart assets, a representation of a real-world resource (e.g., equity, bonds) with a set of rules that govern its behavior, like "can’t be traded until tomorrow" or "can only be sent to US citizens."
One asset traded on the X-Chain is METAL. When you issue a transaction to a blockchain on Avalanche, you pay a fee denominated in METAL.
The X-Chain is an instance of the Avalanche Virtual Machine (AVM). The X-Chain API allows clients to create and trade assets on the X-Chain and other instances of the AVM.