is a mattress with a separate little mattress on the top. This concept was introduced in the 1970's when soft waterbeds became popular. When all beds were firm, the pillow top idea made it possible to make a firm bed with a soft top to compete with soft waterbeds. Often filled with fiber, it is common for these to take body impressions and to compress. Often these body impressions are not under warranty. Pillow Top mattresses are normally sewn right to the mattress. The Savvy Sleeper recommends against fiber pillow tops. Foam pillow tops are usually ok.

a mattress with extra layers of upholstery material sewn into a semi-attached second top

A top finishing on a mattress where a ”pillow“ of soft materials is sewn over the entire surface.