Conduction, Convection and Radiation are the three ways of heat transfer.

What is conduction heat?
When two surfaces contact each other, the surface that is warmer gives off heat to the surface that is cooler which is seen by a glowing burner on a stove contacting & heating the pot. Studs are the primary way this happens in a building because they connect the outer and inner surfaces.

What is convection heat?
The movement of air as a result of air being warmed. Warm air rises seeking the coldest point. The wavy lines you see above a hot road is convection. This is not a problem in the summer but a major concern in the winter.

What is radiant heat?
Radiant heat is an infrared energy such as the heat from the sun. This heat transfers at 18,000 ft per second & is extremely powerful striking cooler objects and transferring the heat to and through them. An example is a car or attic in the summer.