Underfloor Heating uses all three methods of heating: conduction, convection, and radiation:

Conduction: the direct transmission of heat from one body to another through a physical connection.

Convection: transfer of heat through circulating air.

Radiation: transmission of heat in the form of electromagnetic waves or rays.

In comparison with other forms of heating, underfloor heating provides a greater proportion of its heating in the form of radiant heat as typically a large surface area (floor) is warmed which then emits radiant heat into the room across its entire surface area. In effect the floor acts as one very large radiator.