Use $this to refer to the current object. Use self to refer to the current class. In other words, use $this->member for non-static members, use self::$member for static members.
Source: When to use self vs this -stackoverflow
Use $this to refer to the current object. Use self to refer to the current class. In other words, use $this->member for non-static members, use self::$member for static members.
Source: When to use self vs this -stackoverflow
A list of amazingly awesome PHP libraries that you should be using: