What is a 'GlobalCoin' / 'Facebook coin'?

Inquiring minds often wonder about the latest innovations in the world of cryptocurrency. One such topic that has garnered significant attention is the so-called "GlobalCoin" or more colloquially known as the "Facebook coin." Could you elaborate on what this phenomenon is? Specifically, how does it differ from existing cryptocurrencies? Is it backed by any tangible assets? What are the potential benefits and risks associated with its introduction? Understanding the intricacies of this new digital currency could help investors make informed decisions in this rapidly evolving landscape.