The book is a training course on object-oriented programming in C#. Describes the syntax constructs, control statements, and object model used in C#. The publication includes the main topics for studying this programming language, namely: basic data types and operators, control instructions, arrays, classes and objects, inheritance, indexers, properties, delegates, exception handling, multi-threaded programming, operator overloading, Windows development applications and much more. Much attention is paid to creating programs with a graphical interface.