You can also encode "version" information (e.g. $2a$ vs $2y$ for bcrypt) so that, if a vulnerability is discovered in a prior implementation, you can re-hash wi

You can also encode "version" information (e.g. $2a$ vs $2y$ for bcrypt) so that, if a vulnerability is discovered in a prior implementation, you can re-hash with a safe algorithm transparently without having to go "everyone, reset your passwords!"