As an administrator, you can place order on behalf of your customer. The best example of such situation is when your customer call you to place an order because they don't have internet access.

To place an order on behalf of your customer, after you have login as an administrator, type in the username of the user you are ordering for in the Admin order block on the left side of the screen and then click the go button. This field is an auto-complete field, this means that the system will search for the matching username as you type and you can select from the list.

Then, go to the Quote and book page and complete the checkout as if you are the customer.

When you are done, simply click the Switch back link at the Admin order block on the left side of the screen.

Another reason you would use this feature is to allow you to see exactly what the customer's user account can see without knowing that customer's account password.