For many people involved with Bitcoin, altcoins are nothing more than testnets. Hundreds of digital currencies are currently listed on CoinCap.io, but Bitcoin still dominates 78 percent of the market. In total, there are only 10 digital currencies with a current market cap of $10 million or more.
When looking at the most popular altcoins, it’s easy to see that there are some cryptocurrency features that are more desirable than others. Many have said that any altcoin with useful features will eventually see those features incorporated into Bitcoin. Up to this point, it’s clear that many of the most popular altcoins contain features that are similar to new improvements that are planned for Bitcoin.
Ethereum is the most successful altcoin in the history of digital currency ‒ at least when measured as a percentage of Bitcoin’s overall market cap. It was the second altcoin to ever reach a $1 billion market cap (after Litecoin).