slice off the top, stem side, of the apple and then slice the apple into thin rounds, somewhere between 1/8'' to 1/4'' thick. a mandoline slicer works best so they are all the same thickness.
remove the seeds, or the whole core. peel can be left on or taken off.
toss the sliced apples with sinnamon and sugar (optional) and arrange in a single layer in your dehydrator or onto a parchment paper or lined baking pan.
Dehydrator: turn the dehydrator to 135*F. allow the apples to dehydrate for 6-8 hours or until they are dried and as crisp as you want them to be.
Oven: preheat the oven to 200*F. bake the apple slices for 1 hour, then flip them and allow to bake for another 1 to 2 hours until the chips are no longer moist. flipping occasionally.