A skill tree for PHP developer

Please, add learning materials for skills you know! It's like a wikipedia! Community - is the best teacher

Top-2 levels of tree:

PHP Syntax

• Control Structures
• Variables
• Operators
• Types
• Basic syntax
• Classes and Objects
• Constants
• Exceptions
• Namespaces
• Predefined Variables
• Expressions
• Functions
• Errors

JSON APIs

• JSON

OOP

• Design Patterns
• PHP: OOP basics

Relational Databases

• Database Normalization
• SQL Syntax

HTTP

• HTTP body
• HTTP header
• Nginx
• Client Server Architecture

PHP: interfaces

• PHP interfaces: Iterator
• PHP Interface: Serializable
• PHP Interface: ArrayAccess
• PHP interface: Traversable

PHP Framework

• Composer
• Yii
• Wordpress for programmers
• PHP framework laravel
• Symfony

HTML

• CSS
• HTML basic tags