Arduino HandBook is an offline mobile handbook for Arduino aimed at beginners and advanced developers. The app provides a comprehensive guide on Operators, Data, and Functions. The handbook is available in both Русский and English languages, making it accessible to a wide range of users.

The app is easy to use and navigate, with a user-friendly interface. It is an excellent resource for those who need to access information on Arduino programming while on the go. The offline feature is particularly useful for those who do not have access to the internet at all times.

If you require libraries, you can download the "Arduino HandBook 2" application, which is available for Android 4.0+. The app also provides links to social media platforms where users can publish their criticism, request, or feedback.

Please note that any bugs encountered can be reported to the developer via the contact email address provided at the bottom of the app. Overall, this app is highly recommended for Arduino developers of all levels.