It is a plastic material which is thermoformed to the profile of an underlying engineered wood core such as medium-density fiberboard.
Often used for making kitchen cabinet doors, this reasonably priced and commonly available synthetic material is a thin, tight, heat-sealed plastic wrap used to mold over an MDF substrate.
The cabinet boxes that accompany these doors can be finished in various materials such matching thermofoil, coordinating paint, and laminates.
For a budget kitchen remodel, a thermofoil cabinet door is an easy and economical alternative to white paint.
The downside of thermofoil is its greater susceptibility to heat and moisture damage compared to other materials.