Microwaves get their name from their function which is to create electromagnetic rays, like radio waves, to cook or heat food. Rays are generated by a device in the microwave called a magnetron and bounce off the oven’s walls. These rays are then absorbed by the water, sugar and fat within the food. The rays excite these molecules and create heat.
As a result, microwaves cook food from the inside out, which is why the food gets hot, but the air around it doesn’t. Conventional ovens, on the other hand, cook from the outside in, migrating heat by conduction from the outside of the food toward the middle.