From Kook Science

Cryptocurrency (from the Greek κρυπτός, kryptos, "hidden" + the Medieval Latin currentia, "currency") typically refers to a digital scrip token system that exists in the form of cryptographically-signed transactions on a peer-to-peer distributed public ledger, most of these tracing their origins to Bitcoin, a system that was first described in 2009 by an unknown person or group under the name Satoshi Nakamoto. As of early 2022, it is speculated that there are anywhere from over 9000 to 17000 cryptocurrencies in existence; however, of these, the most exchanged tokens are Bitcoin and Ether, the latter being the token on the blockchain that most non-fungible tokens (NFTs) are traded on.