The primary ingredient in traditional apple pie is, of course, apples. Specifically, tart apples, such as Granny Smith or Jonagold, are often used because their acidity and flavor balance well with the sweetness of the pie. The apples are typically peeled, sliced, and tossed with sugar, cinnamon, and sometimes nutmeg, then encased in a flaky pastry crust. Baking allows the apples to soften and release their juices, creating a delicious filling that's both sweet and tangy. Apple pie is a classic dessert, especially popular in the United States, and is frequently associated with celebrations and family gatherings.