This one provides tutorials for all kinds of learners starting with newbies and moving progressively in difficulty to advanced learners. It also has an editor where you can try out your codes and see how they would look like when you use them on your blog or website.
This is also another great platform where you can learn how to write code. Its lessons start from the basics of HTML to advanced forms and styles.
3- Code School
Codea , alas Codify, is a great coding tool for iPad users. It lets students easily create their own apps and program directly on the iPad. They can for instance create games, simulations or any visual idea they have. Codea is not free and costs $9.99.