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.

Apollo is developing an all-in-one cryptocurrency platform, based on the APL coin. Apollo was created as a fork of NXT, and has a very ambitious plan to integrate a variety of services under one platform, with a strong focus on privacy. Apollo's blockchain is called Hermes and has a Proof-of-Stake consensus mechanism. Some of the features that Apollo's marketing materials claim they are working on are: private transactions with IP masking, smart contracts, encrypted messaging, file sharing, a decentralized marketplace, voting system for governance, decentralized data storage, and a wallet with a built in exchange. John McAfee, a notable blockchain enthusiast and antivirus pioneer, joined the project in October 2018.

EOS is a blockchain development platform created by Block.one. Its goal is to become an all purpose operating system for blokchain applications. EOS allows developers to make underlying blockchains and create decentralized application more easily. It was designed from the ground up, to be more scalable and faster than other blockchain platforms. This allows for greater throughput, with more transactions per second, and much lower transaction fees. EOS tokens serve as the native currency. The network has a Delegated Proof-of-Stake (dPoS) consensus mechanism. Transactions are verified by 21 block producers that are chosen through a voting process that is designed to encourage community participation.