Learn about arrays, functions, and classes in PHP.

Sure, let's break down these concepts in PHP:

1. Arrays: An array in PHP is actually an ordered map. A map is a type that associates values to keys. This type is optimized for several different uses; it can be treated as an array, list (vector), hash table (an implementation of a map), dictionary, collection, stack, queue, and probably more.

Here is an example of how to create an array in PHP:

$fruits = array("apple", "banana", "cherry");

2. Functions: A function is a piece of code which takes one more input in the form of parameter and does some processing and returns a value. You already have seen many functions like fopen() and fread() etc. They are built-in functions but PHP gives you option to create your own functions as well.

Here is an example of a function in PHP:

function addNumbers($num1, $num2) {
  $sum = $num1 + $num2;
  return $sum;
}

3. Classes: PHP is a server-side scripting language designed primarily for web development. Using PHP, you can let your user directly interact with the script and easily to learned its syntax. It also has advanced features suitable for professional programming. PHP offers several ways to keep your code organized and reusable. One of the ways is Object Oriented Programming (OOP), and classes are the foundation of OOP.

Here is an example of a class in PHP:

class Car {
  public $color;
  public $model;
  public function __construct($color, $model) {
    $this->color = $color;
    $this->model = $model;
  }
  public function message() {
    return "My car is a " . $this->color . " " . $this->model . "!";
  }
}

I hope this helps! Let me know if you have any other questions.