What are the steps involved in piecing together the complete Internet address in PHP, and why is it necessary to concatenate different parts of the address?

To piece together the complete Internet address in PHP, you need to concatenate different parts of the address such as the protocol (http:// or https://), the domain name, and any additional path or query parameters. This is necessary because each part of the address serves a specific purpose in identifying the location of the resource on the web. By concatenating these parts, you can create a valid and complete URL that can be used to access the desired webpage.

$protocol = 'https://';
$domain = 'www.example.com';
$path = '/index.php';
$query = '?id=123';

$fullUrl = $protocol . $domain . $path . $query;

echo $fullUrl;