“Bitcoin isn’t the only cryptocurrency in town. There are well over 2000 competing cryptocurrencies, known as altcoins,[410] each with its own features, mining algorithms, and (in some cases) blockchains. Some are specialized for particular kinds of payments, others aim to build a platform for apps, and others just seek to improve on Bitcoin’s flaws. Altcoins have gotten bigger and bigger over time — Bitcoin controlled 90% of the cryptocurrency market back in 2015 but just over 60% at the time of writing.”