Following are three methods of heat transfer
Conduction is a mean of heat transfer in solids and transfers heat from one end of a body to another end of the body. When one end of any body is head with the help of some external source then its molecules starts to vibrate at high frequency. Those vibrating molecule have high energy and when they collide with molecules with low energy they transfer some of their energy to that molecule, due to which a chain reaction starts which transfer energy from one end to another end.
Convection is mean of heat transfer between fluids or by fluids. When a fluid is heated with some external source like in boilers then the molecules close to the source of heat absorb some energy or heat and when those molecules collide with other molecules they transfer some of their energy to those molecules. Example of this method is heat transfer by steam to some one hand when place in steam path.
Third method of heat transfer is radiation and in this method heat is transferred with the help of any medium like solid or liquid. Heat is transfer with the help of electromagnetic waves and the perfect example of this is head provided to earth by sun