InnerspringThis is more of a history lesson than a type of mattress you want to shop for (unless you really love this kind of mattress; to each their own). If you're dead set on this mattress type, all power to you, and have fun on your personal mattress treasure hunt. Today, memory foam stands in a league of its own when it comes to the unique, compressive feel. Memory foam is more of an umbrella term for all the iterations mattress brands have come up with today, but let's refer to the mattress manufacturing expert for this one. "Memory foam is produced by combining liquid polyurethane with various chemicals, like polyols and isocyanates, to enhance its viscosity and density," says Merwin.