Changes

'''Fuel''' traditionally is a substance that may be burned to produce [[energy]] (heat, light, or power).  In more recent times fuelds can also be [[nuclear]], and these do not require burning to produce energy.  The chief property of fuel is its caloric value - the amount of heat produced by complete combustion of a unit mass of its volume.

'''Fuel''' traditionally is a substance that may be burned to produce [[energy]] (heat, light, or power).  In more recent times fuels can also be [[nuclear]], and these do not require burning to produce energy.  The chief property of fuel is its caloric value - the amount of heat produced by complete combustion of a unit mass of its volume.

Some fuels that have been found and used throughout history include [[wood]], animal and vegetable oil, [[peat]], [[coal]], and dried dung.

Some fuels that have been found and used throughout history include [[wood]], animal and vegetable oil, [[peat]], [[coal]], and dried dung.