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.

GAS is the token that is used to pay for transaction fees on the NEO network. The NEO platform uses two different tokens; GAS are used to fuel the network and give holders the right to use the NEO blockchain. Similar to Ether on the Ethereum network. Although it's possible to buy GAS on some exchanges, NEO token holders automatically generate GAS as the blockchain increases in size. 8 GAS are distributed for every 100 million NEO in circulation.

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