Bitcoin

Bitcoin (₿) is a decentralized digital currency

Snippet from Wikipedia: Bitcoin

Bitcoin (abbreviation: BTC; sign: ₿) is the first decentralized cryptocurrency. Based on a free-market ideology, bitcoin was invented in 2008 by Satoshi Nakamoto, an unknown entity (person or persons). Use of bitcoin as a currency began in 2009, with the release of its open-source implementation.^{: ch. 1} In 2021, El Salvador adopted it as legal tender. It is mostly seen as an investment and has been described by some scholars as an economic bubble. As bitcoin is pseudonymous, its use by criminals has attracted the attention of regulators, leading to its ban by several countries as of 2021.

Bitcoin works through the collaboration of computers, each of which acts as a node in the peer-to-peer bitcoin network. Each node maintains an independent copy of a public distributed ledger of transactions, called a blockchain, without central oversight. Transactions are validated through the use of cryptography, making it practically impossible for one person to spend another person's bitcoin, as long as the owner of the bitcoin keeps certain sensitive data secret.^{: ch. 5}

Consensus between nodes about the content of the blockchain is achieved using a computationally intensive process based on proof of work, called mining, which is typically performed by purpose-built computers called miners. These miners don't directly act as nodes, but do communicate with nodes. The mining process is primarily intended to prevent double-spending and get all nodes to agree on the content of the blockchain, but it also has desirable side-effects such as making it infeasible for adversaries to stifle valid transactions or alter the historical record of transactions, since doing so generally requires the adversary to have access to more mining power than the rest of the network combined.^{: ch. 12} It is also used to regulate the rate at which new bitcoin is issued and enters circulation. Mining consumes large quantities of electricity and has been criticized for its environmental impact.

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