The following snippet explains how the Gutenberg repository is structured omitting irrelevant or obvious items with further explanations:

│
├── LICENSE
├── README.md
├── SECURITY.md
├── CONTRIBUTING.md
│
├── .editorconfig
├── .eslintignore
├── .eslintrc
├── .jshintignore
├── .eslintignore
├── .prettierrc.js
├── .stylelintignore
├── .stylelintrc.js
├── .markdownlintignore
├── .npmpackagejsonlintrc.json
├── phpcs.xml.dist
│   Dot files and config files used to configure the various linting tools
│   used in the repository (PHP, JS, styles...).
│
├── .browserslistrc
├── babel.config.js
├── jsconfig.json
├── tsconfig.json
├── tsconfig.base.json
├── webpack.config.js
│   Transpilation and bundling Config files.
│
├── .wp-env.json
│   Config file for the development and testing environment.
│   Includes WordPress and the Gutenberg plugin.
│
├── composer.lock
├── composer.json
│   Handling of PHP dependencies. Essentially used for development tools.
│   The production code don't use external PHP dependencies.
│
├── package-lock.json
├── package.json
│   Handling of JavaScript dependencies. Both for development tools and
│   production dependencies.
│   The package.json also serves to define common tasks and scripts
|   used for day to day development.
│
├── changelog.txt
├── readme.txt
│   Readme and Changelog of the Gutenberg plugin hosted on the WordPress
│   plugin repository.
│
├── gutenberg.php
│   Entry point of the Gutenberg plugin.
│
├── post-content.php
│   Demo post content used on the Gutenberg plugin to showcase the editor.
│
├── .github/*
│   Config of the different GitHub features (issues and PR templates, CI, owners).
│
├── bin/api-docs
│   Tool/script used to generate the API Docs.
│
├── bin/packages
│   Set of scripts used to build the WordPress packages.
│
├── bin/plugin
│   Tool use to perform the Gutenberg plugin release and the npm releases as well.
│
├── docs/tool
│   Tool used to generate the Block editor handbook's markdown pages.
│
├── docs/*.md
│   Set of documentation pages composing the [Block editor handbook](https://developer.wordpress.org/block-editor/).
│
├── platform-docs
│   Documentation website targeted to non WordPress developers
│   using Gutenberg in their own applications.
│   Deployed on [https://wordpress.org/gutenberg-framework/](https://wordpress.org/gutenberg-framework/).
│
│
├── lib
│   PHP Source code of the Gutenberg plugin.
│
├── lib/compact/wordpress-x.x
│   PHP code that was include in WordPress ont the WordPress X.X version.
│   It is kept to ensure plugin compatibility with older WordPress versions.
│
├── packages
│   Source code of the WordPress packages.
│   Packages can be:
│    - Production JavaScript scripts and styles loaded on WordPress
│      and the Gutenberg plugin or distributed as npm packages.
│    - Development tools available on npm.
│
├── packages/{packageName}/package.json
│   Dependencies of the current package.
│
├── packages/{packageName}/CHANGELOG.md
├── packages/{packageName}/README.md
│
├── packages/{packageName}/src/**/*.js
├── packages/{packageName}/src/**/*.scss
│   Source code of a given package.
|
├── packages/{packageName}/src/**/*.test.js
│   JavaScript unit tests.
|
├── packages/{packageName}/src/**/{ComponentName}/index.js
│   Entry point of a given component.
|
├── packages/{packageName}/src/**/{ComponentName}/style.scss
│   Style entry point for a given component.
│
├── packages/{packageName}/src/**/{ComponentName}/stories/*.jsx
│   Component Stories to load on the Gutenberg storybook.
│
├── phpunit
│   Unit tests for the PHP code of the Gutenberg plugin.
│
├── storybook
│   Config of the [Gutenberg Storybook](https://wordpress.github.io/gutenberg/).
│
├── test/integration
│   Set of WordPress packages integration tests.
│
├── test/native
│   Configuration for the Gutenberg Mobile unit tests.
│
├── test/unit
│   Configuration for the Packages unit tests.
│
├── test/e2e
│   End-2-end tests of the Gutenberg plugin.
│
├── test/performance
│   Performance metrics. Results are tracked on the [Gutenberg performance dashboard](https://codevitals.run/project/gutenberg).
│
├── tools/eslint
│   Configuration files for the ESLint linter.
│
├── tools/webpack
│   Configuration files for the webpack build.