You have mastered the basics of Python. What's next? This book is a detailed guide to using this programming language in the main application areas - system administration, creating graphical interfaces and web applications. Techniques for working with databases, programming network interactions, creating interfaces for scripts, text processing, and many others are explored. The publication describes the syntax of the language and development methods, contains a large number of examples illustrating typical programming idioms and their correct application. It also explores the effectiveness of Python as a software development tool, as opposed to simply a "scripting" tool. The fourth edition includes new features of the language, libraries, and programming practices for Python Z.H. The examples presented in the book were tested under the third alpha version of Python 3.2. It is safe to say that this thorough and comprehensive book is intended to be the first step towards mastering the mastery of application development in Python.