Many of today's daybeds employ a linkspring as the support system for the mattress. The linkspring is a rectangular metal frame (roughly the footprint of the mattress) with cross supports. A wire or polyester / nylon mesh held in place by a network of springs lies across the top of the linkspring. The linkspring design provides support and creates clearance underneath a daybed for storage.
there are two categories of modern daybeds,indoor and outdoor . Daybeds can be hanging  or stable, outdoor day beds usually have a roof like structure  to protact from sunlight whereas indoor daybeds are simple 
A recent development in infant beds is a bed that converts into a daybed by the removal of one side, ensuring the furniture is useful for more than a couple of years.