Forbes magazine has this to say:
"Cryptocurrency is decentralized digital money, based on blockchain technology. You may be familiar with the most popular versions, Bitcoin and Ethereum, but there are more than 5,000 different cryptocurrencies in circulation, according to CoinLore."
A cryptocurrency is a medium of exchange that is digital, encrypted and decentralized. There is no central
authority that manages and maintains the value of a cryptocurrency. Instead, these tasks are broadly distributed among a cryptocurrency’s users via the internet.
Bitcoin was the first cryptocurrency, first outlined in principle by Satoshi Nakamoto in a 2008 paper titled “Bitcoin: A Peer-to-Peer Electronic Cash System.” Nakamoto described the project as “an electronic payment system based on cryptographic proof instead of trust.”