I often see in many MySQL tutorials that people use command `IDENTIFIED BY 'password'` both during user creation and granting him privileges. 

For example:

```
CREATE USER 'username'@'localhost' IDENTIFIED BY 'password';
GRANT ALL PRIVILEGES ON database.* TO 'username'@'localhost' IDENTIFIED BY 'password';

```

I tried using `GRANT` without `IDENTIFIED BY` and it works.  

Can somebody explain me why it is used twice? Could there be other password for specific privileges?