Order Statuses allows you to create any number of statuses which your orders can be placed in. By default, only the New order status exists, and it is configured to trigger the Order Confirmation email template.
Order statuses can be given a name, and highlight color (which will appear in the Orders Page). If you wish to make this order status the default for new orders, enable the Make Default option. If you select an Email Template, the email will be sent when the order is changed to this status (and when orders are placed if this is the default order status).