Stockfish

<div align="center">

  [![Stockfish][stockfish128-logo]][website-link]

  <h3>Stockfish</h3>

  A free and strong UCI chess engine.
  <br>
  <strong>[Explore Stockfish docs »][wiki-link]</strong>
  <br>
  <br>
  [Report bug][issue-link]
  ·
  [Open a discussion][discussions-link]
  ·
  [Discord][discord-link]
  ·
  [Blog][website-blog-link]

  [![Build][build-badge]][build-link]
  [![License][license-badge]][license-link]
  <br>
  [![Release][release-badge]][release-link]
  [![Commits][commits-badge]][commits-link]
  <br>
  [![Website][website-badge]][website-link]
  [![Fishtest][fishtest-badge]][fishtest-link]
  [![Discord][discord-badge]][discord-link]

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## Overview

[Stockfish][website-link] is a **free and strong UCI chess engine** derived from
Glaurung 2.1 that analyzes chess positions and computes the optimal moves.

Stockfish **does not include a graphical user interface** (GUI) that is required
to display a chessboard and to make it easy to input moves. These GUIs are
developed independently from Stockfish and are available online. **Read the
documentation for your GUI** of choice for information about how to use
Stockfish with it.

See also the Stockfish [documentation][wiki-usage-link] for further usage help.

## Files

This distribution of Stockfish consists of the following files:

  * [README.md][readme-link], the file you are currently reading.

  * [Copying.txt][license-link], a text file containing the GNU General Public
    License version 3.

  * [AUTHORS][authors-link], a text file with the list of authors for the project.

  * [src][src-link], a subdirectory containing the full source code, including a
    Makefile that can be used to compile Stockfish on Unix-like systems.

  * a file with the .nnue extension, storing the neural network for the NNUE
    evaluation. Binary distributions will have this file embedded.

## Contributing

__See [Contributing Guide](CONTRIBUTING.md).__

### Donating hardware

Improving Stockfish requires a massive amount of testing. You can donate your
hardware resources by installing the [Fishtest Worker][worker-link] and viewing
the current tests on [Fishtest][fishtest-link].

### Improving the code

In the [chessprogramming wiki][programming-link], many techniques used in
Stockfish are explained with a lot of background information.
The [section on Stockfish][programmingsf-link] describes many features
and techniques used by Stockfish. However, it is generic rather than
focused on Stockfish's precise implementation.

The engine testing is done on [Fishtest][fishtest-link].
If you want to help improve Stockfish, please read this [guideline][guideline-link]
first, where the basics of Stockfish development are explained.

Discussions about Stockfish take place these days mainly in the Stockfish
[Discord server][discord-link]. This is also the best place to ask questions
about the codebase and how to improve it.

## Compiling Stockfish

Stockfish has support for 32 or 64-bit CPUs, certain har