Codecademy
This was the first site I used and the most interactive and easy-to-use for me. You can keep track of your progress if you sign up and there are loads of nice features, like a Q&A section or a sandbox for messing around with your new knowledge. And you're not just limited to Python - you can learn so many other coding languages like PHP, JavaScript, Ruby, etc. Plus, there are lots of lessons and achievements that will keep you motivated! Definitely a go-to for eager learners.
This is sort of like Codecademy in that there are interactive bits where you can practice and try new exercises. However, it goes more in depth with concepts and what's going on behind all the fancy code. It starts off very easy and approachable and you will be on your way to learning very fast! Popular concepts like recursion and methods are explained as well with loads of "homework" to make sure you've grasped the lesson. Check it out!
6.00x: MIT's Introduction to Computer Science and Programming
One of the best ways to get a move on when learning how to code is to sign up for an online course. They are very in-depth and more like areal class than just self-teaching on the internet. In fact, if you get a passing grade in this course (12 hours/week), you will get an honor code certificate from MITx! It is definitely worth a try if you have commitment and enough time on your hands. MIT has established itself to be the best university for computer science and programming and learning directly from them is an incredible experience.
And finally... your Python Bible
This is not really a course, but more like a reference guide made by the creators of Python! It has all the functions, constants, and types that are in the Python language. You know, the ones that you never bothered to learn (and that's totally fine, because there are hundreds to memorize!). Bookmark this site and constantly refer to it if you are confused, or want to figure out a faster way to do something. Never let go of this Python bible!
That's all I have so far, but I hope that I will be able to add more and more to this list as I learn more programming. Best of luck to everyone!