The book is devoted to programming in C # for the Microsoft .NET platform, from the basics of the language and the development of programs for working in command line mode to the creation of modern web applications. The material is accompanied by a large number of practical examples. The execution logic of each program section is described in detail. Attention is paid to code reuse issues. In the fifth edition, the examples are rewritten taking into account the modern .NET 5 platform, and instead of application applications, the emphasis is on web applications. Although this book is called "Bible C #," it is dedicated to the entire .NET platform from Microsoft. OS, developer tools and the .NET Framework, a developer software framework, have become part of this platform so that we can write applications for the .NET platform. The framework, to simplify the explanation as much as possible, is libraries that provide the programming language with functionality that we can use to write programs. The publisher's website contains program codes, additional reference information and a copy of the database for executing examples from the book.