PHP. Some illegal content.

1. Learn PHP_ Getting Started with PHP Cheatsheet _ Codecademy
2. Learn PHP_ Learn PHP Variables Cheatsheet _ Codecademy
3. Learn PHP_ Introduction to Functions in PHP Cheatsheet _ Codecademy
4. Learn PHP_ PHP Built-in Functions Cheatsheet _ Codecademy
5. Learn PHP_ Learn PHP Arrays Cheatsheet _ Codecademy
6. Learn PHP_ HTML Form Handling in PHP Cheatsheet _ Codecademy
7. Learn PHP_ Conditionals and Logic in PHP Cheatsheet _ Codecademy
8. Learn PHP_ Loops in PHP Cheatsheet _ Codecademy
9. Learn PHP_ PHP Form Validation Cheatsheet _ Codecademy
10. Learn PHP_ Classes and Objects in PHP Cheatsheet _ Codecademy

Thanks to Codecademy for informatively designed material.