Is the $1 billion dollar note real or fake?

Could you please clarify for me, is the $1 billion dollar note being discussed here an actual physical currency note that's in circulation, or is it perhaps a novelty item, a collectible, or even a hoax? I'm genuinely curious about its authenticity, as I've heard of such high-denomination notes existing in some countries, but they're typically not used for everyday transactions. Is there any evidence or documentation to support the legitimacy of this particular $1 billion dollar note? I'd appreciate any information you can provide to help me understand the nature of this note.