Protocol

A protocol is a scheme part of a URL, with an associated wrapper.

In a URL like ftp://www.site.com/file.txt, the protocol is ftp, and relates to the FTP protocol. It is also a predefined PHP wrapper.

<?php

$html = file_get_content('http://www.php.net/');

?>

Documentation

See also Protocols and Wrapper in PHP

Related : Wrapper, Hyper Text Transfer Protocol (HTTP), Hyper Text Transfer Protocol Secure (HTTPS), php://, Stream Wrapper, Stream Wrapper