Each frog is one of a small set of pixel frogs and toads, and no two are the same. Hold the coin, sign a free message with your wallet, and one image is assigned to you. Only your wallet can open it.
Signing is free and sends no transaction. Your frog is a digital image served by this site to the wallet it is assigned to; once downloaded it can be copied, so this controls who gets the file, not what they do with it. The image has no promised value, and the coin can lose all of its value. Nothing here is financial advice. If you sell the coin, this page stops showing your image.