Retainers do one thing, and one thing only. They hold your teeth in their new positions to help achieve stability. They are worn 24/7 to start, then, depending on your compliance, I will be able to shorten the number of hours per day that are required. They come in a variety of shapes, sizes and materials. The 3 most common types, however, are the plastic tray-type retainer (Essex), the wire and plastic retainer (Hawley), and a wire bonded to the insides of your teeth (Bonded 3-3).
Each type of retainer has advantages and disadvantages. I will make the decision with you as which is the most appropriate for maintaining your correction. Your job, then will be to wear the retainer(s) as directed for maximum stability.