A cryptocurrency is a digital asset that is designed as a medium of exchange and is secured in a computerized database using strong cryptography. Ownership of individual coins, transaction records and the control of creation of new coins are assured leveraging cryptographic methods – with built-in functions to prevent counterfeiting and double-spending. Many cryptocurrencies are decentralized networks, utilize blockchain as the underlying technology, and generally function without interference or manipulation of a government or central authority.
As of April 2020, the top 10 cryptocurrencies are are Bitcoin (BTC), Ethereum (ETH), XRP (XRP), Tether (USDT), Bitcoin Cash (BCH) , Litecoin (LTC), EOS (EOS), Binance Coin (BNB), Bitcoin SV (BSV) and Tezos (XTZ) .
Tokens, cryptocurrencies, and other types of digital assets that are not bitcoin are collectively known as alternative cryptocurrencies, typically shortened to “altcoins” or “alt coins”. Paul Vigna of The Wall Street Journal also described altcoins as “alternative versions of bitcoin” given its role as the model protocol for altcoin designers. The term is commonly used to describe coins and tokens created after bitcoin. The list of such cryptocurrencies can be found in the List of cryptocurrencies article.
Altcoins often have underlying differences with bitcoin. For example, Litecoin aims to process a block every 2.5 minutes, rather than bitcoin’s 10 minutes which allows Litecoin to confirm transactions faster than bitcoin.
Another example is Ethereum, which has smart contract functionality that allows decentralized applications to be run on its blockchain. Ethereum is the most-actively used blockchain in the world according to Bloomberg News[more info] and has the largest “following” of any altcoins according to the New York Times.