Create a user
useradd <username>
Create a user with different home directory
useradd -d /Engineers/Projects/ <username>
Create a user with an account expiry date
This is useful if you need to create a temporary account.
useradd -e 2016-02-07 <username>
Add a user to multiple groups
useradd -G admins,webadmin,developer
Delete a user
userdel <username>