Convection is a process of heat transfer by the bulk movement of molecules within fluids such as gases and liquids. The initial heat transfer between the object and the fluid takes place through conduction, but the bulk heat transfer happens due to the motion of the fluid. Convection takes place in liquids and gases, and it is defined as the movement of fluid (liquid and gas) molecules from higher temperature regions to lower temperature regions. There are two types of convection: natural convection and forced convection.

• Natural convection: When convection takes place due to buoyant force as there is a difference in densities caused by the difference in temperatures, it is known as natural convection. An example of natural convection is oceanic winds.

• Forced convection: When external sources such as fans and pumps are used for creating induced convection, it is known as forced convection. Examples of forced convection are using water heaters or geysers for instant heating of water and using a fan on a hot summer day.

Convection gives information about the heat transfer between a surface and a liquid or gas in motion. As the fluid or gas travels faster, the convective heat transfers increase.

In summary, convection is a process of heat transfer by the bulk movement of molecules within fluids such as gases and liquids. It takes place in liquids and gases, and there are two types of convection: natural convection and forced convection.