These are 3 words that I see and hear a lot but don’t use much. Mostly because I can’t keep them straight.

Aun means even or still. Te daré 100 pesos, y aun 200, si los necesitas. I will give you 100 pesos, and even 200, if you need them.

Aún means yet or still. Aún estamos aquí. We are still here.

Aunque is although or even though. Yo comí la vainilla aunque me gusta el chocolate. I ate the vanilla although (even though) I like chocolate.