It’s a bit of a loaded question. “Nan” is the generic term for “bread” in parts of the Middle East, notably Iran, where the word is thought to have originated. However in India “naan” denotes a particular kind of bread, which is to say flat bread that’s baked in a tandoor.
Which raises the question: what’s a tandoor? It’s a pot, basically. A tall, thick clay pot with a charcoal fire at the bottom. Like many types of masonry ovens, tandoors get extremely hot and are great for cooking all sorts of food. You can insert skewers full of meat and vegetables into them, for instance.
If you’re wondering how on Earth you bake in a tall pot with a fire at the bottom, the answer is simple. You slap a moist sheet of dough onto the side of the thing. The thousand-degree heat causes the dough to adhere, and once it’s done you simply peel it off. Easy!
Of course getting the same effect at home is something of a challenge. However naan in one of those breads that are fund to experiment with. You can bake it in pans, on pizza stones, on the grill, under the broiler, anywhere you can bring some big heat to bear. LIke many other simple flat breads, naan is as much a “how” as a “what”. You’ll want to fiddle, I’m sure.