What are Aura cards?

Could you elaborate on the concept of Aura cards? I've heard the term mentioned in the realm of cryptocurrency and finance, but I'm not entirely clear on what they represent or how they function. Are they a form of digital currency? Do they have specific use cases? And how do they integrate into the broader financial ecosystem? I'm particularly interested in understanding their potential value and how investors might approach them as a potential asset class. Could you provide a concise yet comprehensive description of Aura cards?