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

# Introduction

S-two is a state-of-the-art framework for creating STARK proofs that provides the following features:

* A frontend designed to be flexible to allow you to express your own constraints
* A backend that leverages Circle STARKs over the Mersenne31 prime field for fast prover performance
* Seamlessly integrated with Cairo

This book will guide you through the process of creating your own constraints and then proving them using S-two. It will also provide in-depth explanations of the inner workings of how S-two implements Circle STARKs.