> For the complete documentation index, see [llms.txt](https://docs.bitcoinos.build/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.bitcoinos.build/technical-documentation/grail-pro-charms-zkbtc/introduction.md).

# Introduction

Grail Pro is a platform designed to allow the execution of smart contracts directly on the Bitcoin blockchain. This is made possible by leveraging several technologies such as zero-knowledge proofs (ZKP), multiparty computation (MPC) and trusted execution environments (TEE). Grail Pro is a network of secure enclaves that form a decentralized vault capable of locking cryptocurrencies and other tokens, and releasing them according to predetermined conditions. The integrity and security of this system is enforced using ZKP, which can be generated by users and verified inside the enclaves. 

Charms, a ZKP-powered token standard for UTXOs blockchains, allows the creation of smart assets. Each smart asset is a token that has its own logic attached to it. Charms can be made to embody various behaviors, from simple fungible tokens to complicated financial schemes. Charm tokens are blockchain agnostic, which means they can potentially reside on any UTXO-based blockchain, and be transferred easily between blockchains without relying on any counter-party or liquidity provision. 

The first application of Grail Pro is zkBTC, a synthetic Bitcoin token. zkBTC is backed by 100% BTC collateral, and can be redeemed automatically and trustlessly without relying on any counterparty. This serves as a gateway to the Bitcoin OS ecosystem by providing users a

Charm token with real-world value that can be swapped, traded, borrowed, invested or used to pay fees. 

In order to get a better picture of how all this works, let’s consider the pieces individually and then see how they work together to implement various real-world applications. 

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