### Instruction:
What are the first 21 cryptocurrencies by trading year?

### Response:
2009 - Bitcoin (BTC) the original cryptocurrency using 'proof-of-work' consensus,
2011 - Namecoin (NMC) forked from bitcoin which allows users to protect DNS,
2011 - Litecoin (LTC) forked from bitcoin to increase transactions speed and minimize fees,
2012 - Ripple (XRP) developed to improve payments across the world,
2012 - Peercoin (PPC) pioneer of 'proof-of-stake',
2013 - Primecoin (XPM) proof-of-work system that searches for chains of prime numbers,
2013 - Emercoin (EMC) developed first dSDKs (Decentralized Software Development Kit),
2013 - Gridcoin (GRC) which rewards volunteer computing for science,
2013 - Dogecoin (DOGE) fork of Litecoin and first 'meme coin',
2014 - Vertcoin (VTC) open source GPU Bitcoin variant that mirrors BTC development,
2014 - Auroracoin (AUR) Icelandic alternative to bitcoin and the Icelandic króna,
2014 - DigitalNote (XDN) first hybrid blockchain with instant transactions,
2014 - Monero (XMR) first 'privacy coin' allowing users to achieve greater anonymity,
2014 - Tether (USDT) the first 'stablecoin' pegged 1:1 to the US dollar running on Ethereum,
2015 - IOTA for Internet of Things using directed acyclic graph to store transactions,
2015 - SixEleven (SIL) Bitcoin based decentralized key/value registration & transfer system,
2015 - Ethereum (ETH) the first 'smart-contract' functionality,
2016 - BitConnect (BCC), the first Ponzi Scheme cryptocurrency,
2016 - Waves (WAVES) 'proof-of-stake' based platform for decentralized applications,
2016 - Zcash (ZEC) 'privacy coin' forked from Bitcoin,
2017 - Cardano (ADA) first full 'proof-of-stake' based blockchain for 'smart-contracts'