How does fsockopen work in php

Question

I am very new to socket programming. I saw a bit of code like

$fp = fsockopen("www.example.com", 80, $errno, $errstr, 30);
if (!$fp) {
    echo "$errstr ($errno)<br />\n";
} else {
    $out = "GET / HTTP/1.1\r\n";
    $out .= "Host: www.example.com\r\n";
    $out .= "Connection: Close\r\n\r\n";
    fwrite($fp, $out);
    while (!feof($fp)) {
        echo fgets($fp, 128);
    }
    fclose($fp);

At end i see its doing a fwrite. My question is how does it execute the remote php code using fwrite.

Answer 1

This code is connecting to a webserver, and sending an HTTP request, just like a browser would. The remote code executes because that's what the webserver is configured to do when you request that document.