a ruby app. > require 'digest' > print Digest::MD5.hexdigest 'simple_password' + 'reallysaltysalt' bcd6ff334c2d984ecef55859e8a0c564=> nil The above code is self-explanatory. It combines the password with a salt . In simple terms, salt is a random (not necessarily unique) string that is combined with sensitive information and then fed to a hashing algorithm