Bitcoin is the first cryptocurrency created in 2009 by a person or group of people under the name of Satoshi Nakamoto. Bitcoin was proposed as an alternative to the conventional banking system in the wake of the financial crisis of 2008. Unlike banks, the Bitcoin network is a decentralized anonymous peer-to-peer payment system designed to the way that it is almost impossible for a single entity to gain control over this network.
DigitalNote (XDN) cryptocurrency is currently listed on the number of exchanges against cryptos (BTC or ETH). It emerged in 2015 as a Fair Launch, which did not imply any reward for developers, ICO campaign or premined blocks . Recently, XDN held a swap to the XDN 2.0 network with improved functionality.
Zcash (ZEC) is a cryptocurrency with strong cryptography that is supposed to provide high security and privacy. At some point, Zcash was endorsed by Edward Snowden and Roger Ver. Zcash is a Bitcoin fork and it exists since 2016. The mechanism providing privacy is called zero-knowledge proofs (or zk-SNARKS).