What cryptocurrencies are there?

As of February 2021, there are 4081 cryptocurrencies or tokens that are currently listed on the coinmarketcap.com website. The vast majority will probably never have much value and will probably disappear someday. Bitcoins are the major cryptocurrency; the altcoins are alternatives to the Bitcoin cryptocurrency while the tokens are cryptocurrencies that are built as decentralized “applications” i.e. they don’t have their own blockchain, but they use the blockchain of some other true cryptocurrency.