Emacs has a lot of keyboard shortcuts, and many people like to customize them extensively. Finding efficient, available combinations is not trivial. This virtual keyboard shows on first glance which keys are in use with which modifier combinations.

There is a blog post about it, if you are interested in understanding all of its features and use cases: https://tkainrad.dev/posts/visualize-collections-of-keyboard...

KeyCombiner has similar public visualizations for other IDEs and applications:

VSCode: https://keycombiner.com/collections/vscode/

IntelliJ IDEA: https://keycombiner.com/collections/intellij-idea/

XCode: https://keycombiner.com/collections/xcode/