An air fryer's primary use is to cook, crisp, and reheat food using rapid, hot air circulation, mimicking the effects of deep frying but with significantly less oil, making it a healthier option. You can use it to cook classic fried items, roast vegetables, bake small goods like cookies, grill proteins like chicken and steak, and evenly reheat leftovers, offering a versatile, efficient, and healthier alternative to traditional cooking methods like deep frying or even a full-sized oven