Bitcoin is the first digital currency based on blockchain. It solved the double-spending problem and enabled peer-to-peer transactions on a large scale. Bitcoin was designed to work as a trustless digital currency that would function without government oversight or a central bank.
Bitcoin was developed by Satoshi Nakamoto, whose identity has never been confirmed and has become the subject of great intrigue. Bitcoin builds upon on other cryptographic and digital currency projects that came before it, but its use of blockchain made it more viable. Nakamoto originally released his white paper and open-source software on a cryptography forum. He mined the first block of the Bitcoin chain, called the genesis block in January 2009.
Bitcoins are created as a reward for a process known as mining. One of the core innovations of Bitcoin, is its consensus algorithm, which creates an incentive system that rewards miners for confirming transactions.
Hal Finney, who developed the first reusable proof-of-work system (RPOW), several years before, was the first Bitcoin adopter and received the first bitcoin transaction ever recorded on its blockchain.

Bitcoin Cash SV is a cryptocurrency that was created as a result of a hard fork of the Bitcoin Cash blockchain that occurred on November 15, 2018. The central issue that led to the hard fork of Bitcoin Cash was a debate among prominent members of the Bitcoin Cash community regarding block size. A larger block size can improve transaction times, but also lead to greater network centralization. Roger Ver, an influential cryptocurrency advocate, was one of the central figures in favor of keeping the smaller 32 MB block size, while Craig Wright, the chief scientist at nChain, favored a larger 128 MB block size. The division between these two factions led to the hard fork that created Bitcoin Cash ABC and Bitcoin Cash SV.

Eternal is a Japanese cryptocurrency project that consists of Eternal Coin (XEC) and Eternal Token (XET). The project appears to be primarily focused on remittance payments, but can also be used as a medium of exchange for other purposes. XEC holders receive weekly dividend payments, and can only be traded through the company's authorized exchanges. XET was created to allow users to trade XEC on other crypto exchanges. 1 XET=10 XEC.