Bitcoin was the pioneer in crypto currencies.After that,altcoins like ethereum,monero,zcash were created which had atleast some unique features which were missing in bitcoin like anonymity,tc.But later,many people tarted to create altcoins just to make some quick profits and they were termed as shitcoins.They were hundreds in numbers today.They do not deliver any thing unique.They were just pumped and dumped and it would be better to stay away from them.