Send $_POST Request Using PHP cURL

send_POST_request_using_cURL.php

//extract data from the post
//set POST variables
$url = 'http://domain.com/get-post.php';
$fields = array(
	'lname' => urlencode($_POST['last_name']),
	'fname' => urlencode($_POST['first_name']),
	'title' => urlencode($_POST['title']),
	'company' => urlencode($_POST['institution']),
	'age' => urlencode($_POST['age']),
	'email' => urlencode($_POST['email']),
	'phone' => urlencode($_POST['phone'])
);

//url-ify the data for the POST
foreach($fields as $key=>$value) { $fields_string .= $key.'='.$value.'&'; }
rtrim($fields_string, '&');

//open connection
$ch = curl_init();

//set the url, number of POST vars, POST data
curl_setopt($ch,CURLOPT_URL, $url);
curl_setopt($ch,CURLOPT_POST, count($fields));
curl_setopt($ch,CURLOPT_POSTFIELDS, $fields_string);

//execute post
$result = curl_exec($ch);

//close connection
curl_close($ch);

Can you explain me what the command: "foreach($fields as $key=>$value) { $fields_string .= $key.'='.$value.'&'; }" do?