Air fryers make use of hot air to cook the food from all around. It is a patented technology called Rapid Air Technology which uses high speed circulation to circulate the air around the food items placed in the basket. This makes this method a fast and healthy way to cook food which makes the food item crispy from the outside without being dry from the inside.
Traditionally food items need oil to cook. However, in Air fryers, only hot air is used to cook food. For example, if you make deeply friend french fries using the conventional method and using Air frier, in the latter, the fat content is 80% less. Not to mention this technology drastically reduces the time required to cook the food items.