What is the difference between public, private, and protected?

What is the difference between public, private, and protected?

php oop private public protected

php

Call-time pass-by-reference has been removed [duplicate]

php class function pass-by-reference public

php

Setting public class variables

php variables public

php

Does static method in PHP have any difference with non-static method?

php static public

php

Access Level to certain class must be public error in PHP

php dry abstract public

php

PHP classes why use public keyword?

php class public

php

CakePHP "Fatal error: Class 'Debugger' not found" in a File That Doesn't Reference Debugger

php cakephp-2.0 public

php