Bitcoin is a digital currency created in January 2009 following the housing market crash. It follows the ideas set out in a whitepaper by the mysterious and pseudonymous Satoshi Nakamoto. The identity of the person or persons who created the technology is still a mystery. Bitcoin offers the promise of lower transaction fees than traditional online payment mechanisms and is operated by a decentralized authority, unlike government-issued currencies.
There are no physical bitcoins, only balances kept on a public ledger that everyone has transparent access to, that – along with all Bitcoin transactions – is verified by a massive amount of computing power. Bitcoins are not issued or backed by any banks or governments, nor are individual bitcoins valuable as a commodity.
It is one of the first digital currencies to use peer-to-peer technology to facilitate instant payments. The independent individuals and companies who own the governing computing power and participate in the Bitcoin network, are comprised of nodes or miners. "Miners," or the people who process the transactions on the blockchain, are motivated by rewards (the release of new bitcoin) and transaction fees paid in bitcoin. These miners can be thought of as the decentralized authority enforcing the credibility of the Bitcoin network.
New bitcoin is being released to the miners at a fixed, but periodically declining rate, such that the total supply of bitcoins approaches 21 million. Currently, there are roughly 3 million bitcoins which have yet to be mined. In this way, Bitcoin (and any cryptocurrency generated through a similar process) operates differently from fiat currency; in centralized banking systems, currency is released at a rate matching the growth in goods in an attempt to maintain price stability, while a decentralized system like Bitcoin sets the release rate ahead of time and according to an algorithm.
Bitcoin mining is the process by which bitcoins are released into circulation. Generally, mining requires the solving of computationally difficult puzzles in order to discover a new block, which is added to the blockchain. In contributing to the blockchain, mining adds and verifies transaction records across the network. For adding blocks to the blockchain, miners receive a reward in the form of a few bitcoins; the reward is halved every 210,000 blocks.
The block reward was 50 new bitcoins in 2009 and is currently 12.5. By around May 11th, 2020 the next halving will occur, bringing the reward for each block discovery down to 6.25 bitcoins. A variety of hardware can be used to mine bitcoin but some yield higher rewards than others.
Certain computer chips called Application-Specific Integrated Circuits (ASIC) and more advanced processing units like Graphic Processing Units (GPUs) can achieve more rewards. These elaborate mining processors are known as "mining rigs." One bitcoin is divisible to eight decimal places (100 millionths of one bitcoin), and this smallest unit is referred to as a Satoshi. If necessary, and if the participating miners accept the change, Bitcoin could eventually be made divisible to even more decimal places.