Altcoins are cryptocurrencies other than bitcoin. Many altcoins are forks (variations) of bitcoin.
“Altcoin” is a combination of two words: “alt” and “coin”. The word “alt” is short for alternative and “coin” means currency.
Together, they imply cryptocurrencies that are an alternative to the original cryptocurrency named bitcoin.
Many altcoins have emerged but bitcoin still remains the largest and most popular of all cryptocurrencies.