Although the term cryptocurrencies are used to define all the different types of cryptocurrency or digital currencies, it is commonly interchanged with coins. They are commonly regarded so despite many of them not serving as a unit of account, store of value, and a medium of exchange, although Bitcoin does.
However, coins can be differentiated from altcoins. The term altcoins is also a common reference to cryptocurrencies of all types apart from Bitcoin, in that they are seen as an alternative to Bitcoin.
Coins: Coins can be differentiated from altcoins because they are based on their blockchain. On such a blockchain, they act as the native token as well as gas or fuel payment token, although a blockchain can have the gas paid in a different cryptocurrency. A good example is Bitcoin on the Bitcoin and Ether or ETH on the Ethereum blockchain.
In terms of constructing or developing a cryptocurrency, it starts or comes along with developing a blockchain.
Altcoins: Although these can be regarded as coins, they are all understood to be alternatives to Bitcoin as the first cryptocurrency. Also known as shitcoins, apart from Ethereum, most of the first ones were forked from Bitcoin. These include Namecoin, Peercoin, Litecoin, Dogecoin, and Auroracoin.
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