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

# Fault proofs

> One place to learn the OP Stack fault proof system, from the gentle introduction through the components, hands-on guides, bond economics, and the normative spec.

Fault proofs are how OP Stack chains secure withdrawals without a trusted
third party: anyone can propose the state of the chain on Ethereum, and
anyone can challenge a proposal they believe is wrong. A dispute is
narrowed down, through a bisection game, to a single instruction of
execution, and that one instruction is proven on Ethereum inside an onchain
virtual machine.

This page is the recommended reading order for the whole topic. Start with
the explainer for the mental model, work through the component pages to see
how the pieces fit, then use the hands-on guides if you operate a chain or
want to run a challenger. The bond economics and the normative spec close
the loop for readers who need full depth. Every stop is an existing page;
nothing here replaces them.

## Start here

* [Fault proofs explainer](/op-stack/fault-proofs/explainer): read this
  first for the mental model, covering permissionless proposals,
  permissionless challenges, and the Guardian backstop behind both.

## Go deeper

* [FP system components](/op-stack/fault-proofs/fp-components): the three
  modules of the system (fault proof program, fault proof virtual machine,
  dispute game protocol), why they are decoupled, and why `kona-client` is
  the default fault proof program today.
* [Fault proof VM: Cannon](/op-stack/fault-proofs/cannon): the default
  fault proof virtual machine, split between the onchain `MIPS64.sol`
  contract and the offchain `mipsevm` Go implementation.
* [Fault proof VM: MIPS64.sol](/op-stack/fault-proofs/mips): the onchain
  half at instruction level, an EVM implementation of the multithreaded
  64-bit MIPS instruction set.
* [OP-Challenger explainer](/op-stack/fault-proofs/challenger): how the
  honest actor detects faults, and how it defends valid proposals and
  counters invalid claims move by move.

## Get hands-on

* [Run a fault-proof challenger](/use-cases/run-a-fault-proof-challenger):
  the end-to-end path to a challenger that defends a chain, from bond
  budgeting and prestate selection through infrastructure, configuration,
  and monitoring.
* [How to configure challenger for your chain](/chain-operators/guides/configuration/op-challenger-config-guide):
  the per-flag configuration walkthrough behind that path.
* [Challenger configuration reference](/chain-operators/reference/challenger-configuration):
  the full catalogue of `op-challenger` flags, environment variables, and
  defaults to keep open while you configure.
* [Generating absolute prestate and preimage files](/chain-operators/tutorials/absolute-prestate):
  build and verify the `kona-client` absolute prestate that anchors every
  dispute for your chain.
* [Migrating to permissionless fault proofs](/chain-operators/tutorials/migrating-permissionless):
  move a chain from the permissioned dispute game to permissionless fault
  proofs in four phases.
* [Chain monitoring options](/chain-operators/tools/chain-monitoring#dispute-mon):
  run `op-dispute-mon`, the security monitoring service that tracks the
  status of every game over the last 28 days.

## Economics and incentives

* [Fault proofs explainer FAQs](/op-stack/fault-proofs/explainer#faqs):
  what proposals cost a chain operator to run and how bonds are sized to
  deter invalid claims.
* [OP-Challenger explainer FAQs](/op-stack/fault-proofs/challenger#faqs):
  what the bond does, how much ETH a full-depth game can require, and the
  infrastructure questions (like blob retention) that decide whether you
  can win.

## The normative spec

The definitive definition of fault proof behavior lives in the OP Stack
specifications:

* [Fault proof](https://specs.optimism.io/fault-proof/index.html?utm_source=op-docs\&utm_medium=docs):
  the fault proof program and the pre-image oracle it reads from.
* [Fault dispute game](https://specs.optimism.io/fault-proof/stage-one/fault-dispute-game.html?utm_source=op-docs\&utm_medium=docs):
  the game itself, including bisection, clocks, and resolution.
* [Honest challenger](https://specs.optimism.io/fault-proof/stage-one/honest-challenger-fdg.html?utm_source=op-docs\&utm_medium=docs):
  the behavior an honest challenger must implement, which `op-challenger`
  follows.
* [Bond incentives](https://specs.optimism.io/fault-proof/stage-one/bond-incentives.html?utm_source=op-docs\&utm_medium=docs):
  the normative bond economics behind the FAQ answers above.
* [Multithreaded Cannon fault proof VM](https://specs.optimism.io/fault-proof/cannon-fault-proof-vm.html?utm_source=op-docs\&utm_medium=docs):
  the specification of the FPVM that Cannon implements.

## Audits and security

* [Fault proofs security](/op-stack/fault-proofs/fp-security): the
  security model and its safeguards, including the Guardian role, game
  blacklisting, the global pause, and delayed bond payouts through
  `DelayedWETH`.
* [Audit reports](/op-stack/security/audit-reports): the standing index of
  OP Stack security reviews, which routes to the full list in the
  monorepo.