Dive Into Python offered by Mark Pilgrim is a cost-free software guide that teaches Python.
Dive Into Python is released under the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation. You have consent to copy, distribute, and/or modify this document without any Invariant Sections, Front-Cover Texts, and Back-Cover Texts. The GNU Free Documentation License is included in Appendix G of the tutorial, so you can ensure that you have access to the complete license agreement.
Additionally, the example programs in the tutorial are free software, and you are free to redistribute and/or modify them under the terms of the Python license as published by the Python Software Foundation. A copy of the Python license is included in Appendix H of the tutorial. This means that you can learn from the examples and even use them in your own projects without worrying about any legal issues.
Overall, Dive Into Python is an excellent and comprehensive Python tutorial, providing you with all the basic information you need to start learning the language. The fact that it is freely available and comes with a clear licensing agreement makes it an ideal resource for both beginner and experienced Python users.