Darkcoin (Dash): Darkcoin, known as Dash as of March 25, 2015 (dash=digital cash), but previously known as XCoin, has unique functionality. XCoin was developed by Evan Duffield who wanted to improve on Bitcoin but didn’t have the pull to do so. Thus, he developed his own coin. It takes less power to mine Dash than most coins. Using less energy to mine is important because mining coins is one of the most wasteful processes you can imagine. The wasteful mining process is key to security and stability of all coins that use a “proof-of-work” system. It prevents people from mining too fast. However, environmentally, it’s a nightmare. In 2015 we had said, “People know what a Darkcoin is. Hopefully, this familiarity rolls over to Dash” (today few remember XCoin and Darkcoin, and Dash is a well-known crypto). Back in 2015, Dash was one of the higher valued coins. Today that is still true, and Dash has performed almost as well competitors like Ethereum.
In 1998, Wei Dai published a description of "b-money", characterized as an anonymous, distributed electronic cash system. Shortly thereafter, Nick Szabo described bit gold. Like bitcoin and other cryptocurrencies that would follow it, bit gold (not to be confused with the later gold-based exchange, BitGold) was described as an electronic currency system which required users to complete a proof of work function with solutions being cryptographically put together and published. A currency system based on a reusable proof of work was later created by Hal Finney who followed the work of Dai and Szabo.