A blockchain is a growing set of documents, referred to as blocks, that are linked together via encryption to form a single chain of transactions. Each block includes a hash code of the preceding block, as well as a timestamp and the data associated with the transaction (generally represented as a Merkle tree). In order to get into the hash of a block, the timestamp must confirm that the transaction data existed at the moment the block was released. Because each block contains information about the one before it, the blocks together create a chain, with each successive block strengthening the knowledge contained in the blocks before it. In order to prevent data tampering, blockchains must be recorded in such a way that the data in any one block cannot be changed retrospectively without affecting all of the succeeding blocks.
For usage as a publicly distributed ledger, blockchains are often controlled by a peer-to-peer network that adheres to a protocol in order to communicate and verify new blocks. However, since forks are conceivable, blockchain records cannot be deemed unalterable. Instead, blockchains may be considered safe by design and serve as an example of a distributed computing system with high Byzantine fault tolerance.
The blockchain, which was popularised by a person (or group of people) going by the name Satoshi Nakamoto in 2008 to serve as the public transaction ledger for the cryptocurrency bitcoin, was based on work by Stuart Haber, W. Scott Stornetta, and Dave Bayer and was created by a person or group of people going by the name Satoshi Nakamoto in 2008. The identity of Satoshi Nakamoto has remained a mystery to this day. When bitcoin was created, it became the first digital money to address the double-spending issue without the requirement for a trusted authority or central server. Bitcoin was the first digital currency to accomplish so. As a result of the bitcoin architecture, several new apps and blockchains have emerged that are accessible to the general public and are extensively utilised by cryptocurrencies. The blockchain is seen as a form of payment rail in certain circles. Private blockchains have been suggested for commercial usage, however the marketing of such privatised blockchains without a solid security model has been dubbed "snake oil" according to Computerworld magazine. Others, on the other hand, have claimed that permissioned blockchains, if they are well structured, may be more decentralised and, as a result, more secure in reality than permissionless blockchains.