In mattress terms, firmness and support almost go hand-in-hand. Support refers to a bed's ability to keep your back, neck, head, trunk and lower body propped and in proper alignment. Firmer beds tend to have the most support because they keep your body from sinking into the foam.  When a bed like the Casper models have zoned support designs, it means it's firmer under your back for ample support, and more soft pressure-relieving around your shoulders and trunk for more pressure relief.