Air fryers work like a convection oven to circulate air around your food and cook it evenly from every angle. That means any fat you add to the air fryer will circulate around your fries, chicken or fish as it cooks, making it crisp and crunchy.
Air fryers typically come with an in-built basket that has space for air to get underneath your food, as well as cooking it from above and the side. In the Ninja Dual Zone for example, you can remove this and use the tray like a regular oven tray to add a crisp cheesy top to a pasta bake or roast vegetables and potatoes for convenient mealtimes.