The third version of the Python language has made it even more powerful, convenient, logical and expressive. The book "Programming in Python 3" was written by one of the leading experts in this language, with many years of experience working with it. The publication contains everything you need for practical mastery of the language: writing any programs using both the standard library and third-party libraries for the Python 3 language, as well as creating your own library modules. The author begins with a description of the key elements of Python, the knowledge of which is necessary as basic concepts. More advanced topics are then discussed, presented in a way that allows the reader to gradually increase their experience: distributing the computational load across multiple processes and threads, using complex data types, control structures and functions, and creating applications that work with SQL databases and DBM files. The book can serve as both a textbook and a reference book. The text is accompanied by numerous examples available on the publication’s special website. All example code has been tested with the final release of Python 3 on Windows, Linux, and Mac OS X.