MD5 Encryption & Password Saving in PHP function

In this video MD5 Message-Digest Algorithm takes as input a message of arbitrary length and produces as output a 128-bit "fingerprint" or "message digest" of the input. The MD5 algorithm is intended for digital signature applications, where a large file must be "compressed" in a secure manner before being encrypted with a private (secret) key under a public-key cryptosystem such as RSA." The Syntax of the PHP function is md5(string,raw) .