Which of the methods of heat transfer is the heating of solids based on?

Solid bodies in the world around us are characterized by the presence of certain qualities and properties, which include, in particular, a phenomenon (sign) called “thermal conductivity”. In relation to solids, this term is usually used to denote a physical phenomenon that manifests itself in the ability to transfer an energy flow (heat) from a more heated part (element) to a less heated one. Thus, the process of heat transfer in physical science is based on the phenomenon of heat conduction.

Answer. Thermal conductivity.