This book teaches application-level programming with Python. That is, it is about what you can do with the language once you've mastered its fundamentals.

By reading this book, you will learn to use Python in some of its most common roles: to build GUIs, web sites, networked tools, scripting interfaces, system administration programs, database and text processing utilities, and more.

Along the way, you will also learn how to use the Python language in realistically scaled programsconcepts such as object-oriented programming (OOP) and code reuse are recurring side themes throughout this text. And you will gain enough information to further explore the application domains introduced in the book, as well as to explore others.

Now that I've told you what this book is, I should tell you what it is not. First of all, this book is not a reference manual. Although the index can be used to hunt for information, this text is not a dry collection of facts; it is designed to be read. And while many larger examples are presented along the way, this book is also not just a collection of minimally documented code samples.

Rather, this book is a tutorial that teaches the most common Python application domains from the ground up. It covers each of Python's target domains gradually, beginning with in-depth discussions of core concepts in each domain, before progressing toward complete programs. Large examples do appear, but only after you've learned enough to understand their techniques and code.

For example, network scripting begins with coverage of network basics and protocols and progresses through sockets, client-side tools, HTML and CGI fundamentals, and web frameworks. GUI programming gets a similarly gentle presentation, with one introductory and two tutorial chapters, before reaching larger, complete programs. And system interfaces are explored carefully before being applied in real and useful scripts.

In a sense, this book is to application-level programming what the book Learning Python is to the core Python languagea learning resource that makes no assumptions about your prior experience in the domains it covers. Because of this focus, this book is designed to be a natural follow-up to the core language material in Learning Python and a next step on the way to mastering the many facets of Python programming.

In deference to all the topic suggestions I have received over the years, I should also point out that this book is not intended to be an in-depth look at specific systems or tools. With perhaps one million Python users in the world today, it would be impossible to cover in a useful way every Python-related system that is of interest to users.