> ## 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.

# Glossary

*This document contains definitions for terms used throughout the Kona book.*

#### Fault Proof VM

A `Fault Proof VM` is a virtual machine, commonly supporting a subset of the Linux kernel's syscalls and a modified subset of an existing reduced instruction set architecture,
that is designed to execute verifiable programs.

Full specification for the `cannon` & `cannon-rs` FPVMs, as an example, is available in the [Optimism Monorepo][cannon-specs].

#### Fault Proof Program

A `Fault Proof Program` is a program, commonly written in a general-purpose language such as Golang, C, or Rust, that may be compiled down
to a compatible `Fault Proof VM` target and provably executed on that target VM.

Examples of `Fault Proof Programs` include the [OP Program][op-program], which runs on top of [`cannon`][cannon], [`cannon-rs`][cannon-rs], and
[`asterisc`][asterisc] to verify a claim about the state of an [OP Stack][op-stack] layer two.

#### Preimage ABI

The `Preimage ABI` is a specification for a synchronous communication protocol between a `client` and a `host` that is used to request and read data from the `host`'s
datastore. Full specifications for the `Preimage ABI` are available in the [Optimism Monorepo][preimage-specs].

[op-stack]: https://github.com/ethereum-optimism/optimism

[op-program]: https://github.com/ethereum-optimism/optimism/tree/develop/op-program

[cannon]: https://github.com/ethereum-optimism/optimism/tree/develop/cannon

[cannon-rs]: https://github.com/op-rs/cannon-rs

[asterisc]: https://github.com/ethereum-optimism/asterisc

[fp-specs]: https://specs.optimism.io/experimental/fault-proof/index.html

[fpp-specs]: https://specs.optimism.io/experimental/fault-proof/index.html#fault-proof-program

[preimage-specs]: https://specs.optimism.io/experimental/fault-proof/index.html#pre-image-oracle

[cannon-specs]: https://specs.optimism.io/experimental/fault-proof/cannon-fault-proof-vm.html#cannon-fault-proof-virtual-machine

[l2-output-root]: https://specs.optimism.io/protocol/proposals.html#l2-output-commitment-construction

[op-succinct]: https://github.com/succinctlabs/op-succinct

[revm]: https://github.com/bluealloy/revm

[kona]: https://github.com/ethereum-optimism/optimism/tree/develop/rust/kona

[issues]: https://github.com/ethereum-optimism/optimism/issues

[new-issue]: https://github.com/ethereum-optimism/optimism/issues/new

[contributing]: https://github.com/ethereum-optimism/optimism/tree/develop/rust/kona/CONTRIBUTING.md

[op-labs]: https://github.com/ethereum-optimism

[bad-boi-labs]: https://github.com/BadBoiLabs