Bitcoin (BTC) is a peer-to-peer digital currency intended to function as a medium of exchange independent of any central authority. BTC can be transferred electronically in a secure, verifiable, and irreversible manner.
BTC was launched in 2009, and it is the first virtual currency to solve the double-spending problem by timestamping transactions before broadcasting them to all nodes in the Bitcoin network. The Bitcoin protocol provided a solution to the Byzantine generals' problem through the structure of the blockchain, a concept first introduced by Stuart Haber and W. Scott Stornetta in 1991.
The Bitcoin whitepaper was published in 2008 by an individual or group under the pseudonym "Satoshi Nakamoto," whose true identity has yet to be verified.
The Bitcoin protocol uses a proof-of-work (PoW) algorithm based on SHA-256d to achieve network consensus. Its target block creation time is 10 minutes, and the maximum supply is 21 million tokens, with a decreasing token issuance rate. To prevent fluctuations in block creation time, the difficulty of the network's blocks is adjusted using an algorithm based on the block creation times of the previous 2016 blocks.
With a maximum block size of 1 megabyte, the Bitcoin protocol supports both the Lightning Network, which is a second-layer infrastructure for payment channels, and the separate witness, which is a protocol upgrade to increase the number of transactions in a block, as solutions for network scalability.
