Difference between "" and localhost in mysql.host

[Pavel Ondrej]

Hello,

please can you explain me what is differnce between

select Host,Db from mysql.host;

*************************** 1. row ***************************
Host: localhost
Db: %

and

*************************** 2. row ***************************
Host:
Db: %

When is only localhost in host table, so I have problem with select database (sometimes). In users table are all users with host="".

Thank you

Pavel