Basic purpose of this lecture is to present on Heat Transfer. It is a tutorial based lecture. If there is a temperature difference between two systems heat will always find a way to transfer from the higher to lower system. Conduction is the transfer of heat between substances that are in direct contact with each other. Thermal energy is transferred from hot places to cold places by convection. Convection occurs when warmer areas of a liquid or gas rise to cooler areas in the liquid or gas. Radiation is a method of heat transfer that does not rely upon any contact between the heat source and the heated object as is the case with conduction and convection.