An altcoin, short for “alternative coin,” is a term used to describe any cryptocurrency that isn’t Bitcoin. Bitcoin was the first established cryptocurrency, and all subsequent cryptocurrencies are generally referred to as altcoins.
Some altcoins are variations (or “forks”) of Bitcoin, built using Bitcoin’s open-source protocol. They introduce changes to Bitcoin’s underlying technology, such as altering the transaction speed, the consensus algorithm, or the privacy features. Examples of these types of altcoins include Bitcoin Cash and Bitcoin SV.
Other altcoins, however, are built from scratch and offer entirely different functionalities and use cases. For example, Ethereum, the second largest cryptocurrency by market cap, introduced smart contracts and decentralized applications (dApps) to the blockchain ecosystem.