Show users
SELECT user, host, password FROM mysql.user;

Create new user accessible only on localhost
CREATE USER '[User1]'@'localhost' IDENTIFIED BY '[password]';

Create new user accessible from anywhere
CREATE USER '[User1]'@'%' IDENTIFIED BY '[password]';

Grant permissions to all databases for User1 from localhost only
GRANT ALL PRIVILEGES ON *.* TO 'User1'@'localhost' WITH GRANT OPTION;

Grant permissions to specified database for User1 from anywhere
GRANT ALL PRIVILEGES ON [db_name].* TO 'User1'@'%' WITH GRANT OPTION;

Create a new user and grant permissions to database at once
GRANT ALL PRIVILEGES ON [db_name].* To 'user'@'hostname' IDENTIFIED BY '[password]';

Show users permissions
SHOW GRANTS FOR [username]@localhost;