Another (lesser) benefit of a salt is as follows: two users might choose the same string as their password, or the same user might choose to use the same password on two machines. Without a salt, this password would be stored as the same hash string in the password file. This would disclose the fact that the two accounts have the same password, allowing anyone who knows one of the account's passwords to access the other account. By salting the passwords with two random characters, even if two accounts use the same password, no one can discover this just by reading hashes.