Here is the text of the NIST sp800-63b Digital Identity Guidelines.
Salt the hash with something unique to that specific user so identical passwords have different hashes
Isn’t that… the very definition of a Salt? A user-specific known string? Though my understanding is that the salt gets appended to the user-provided password, hashed and then checked against the record, so I wouldn’t say that the hash is salted, but rather the password.
Also using a pepper is good practice in addition to a salt, though the latter is more important.
Some implementers reuse the same salt for all passwords. It’s not the worst thing ever, but it does make it substantially easier to crack than if everything has its own salt.
That’s a pepper not a salt. A constant value added to the password that’s the same for every user is a pepper and prevents rainbow table attacks. A per-user value added is a salt and prevents a number of things, but the big one is being able to overwrite a users password entry with another known users password (perhaps with a SQL injection).
