A __blockchain__, is a growing list of Record (computer science), called ''blocks'', which are linked using cryptography. Each block contains a Cryptographic hash function of the previous block, a Trusted timestamping, and transaction data (generally represented as a merkle tree root hash) - wikipedia 
YOUTUBE 3FA3UjA0igY Nick Szabo and Tim Ferriss discuss Blockchain
By design, a blockchain is resistant to modification of the data. It is "an open, distributed ledger that can record transactions between two parties efficiently and in a verifiable and permanent way".
- See also Block chain
For use as a distributed ledger, a blockchain is typically managed by a peer-to-peer network collectively adhering to a Protocol (communication) for inter-node communication and validating new blocks.
YOUTUBE 19QT8-i1Wf0 Coinscrum (Apr 2014) - The Concept of the Blockchain
Once recorded, the data in any given block cannot be altered retroactively without alteration of all subsequent blocks, which requires consensus of the network majority. Although blockchain records are not unalterable, blockchains may be considered secure by design and exemplify a distributed computing system with high Byzantine fault tolerance. Decentralized consensus has therefore been claimed with a blockchain.
Blockchain. distributed data store for digital transactions
- wikimedia.org
Blockchain was invented by Satoshi Nakamoto in 2008 to serve as the public transaction ledger of the cryptocurrency bitcoin. and blockchains which are readable by the public are widely used by cryptocurrencies. Blockchain is considered a type of payment rail. Private blockchains have been proposed for business use. Sources such as the ''Computerworld'' called the marketing of such blockchains without a proper security model "snake oil".
# History
The first work on a cryptographically secured chain of blocks was described in 1991 by Stuart Haber and W. Scott Stornetta. They wanted to implement a system where document timestamps could not be tampered with.
In 1992, Bayer, Haber and Stornetta incorporated Merkle trees to the design, which improved its efficiency by allowing several document certificates to be collected into one block - wikipedia
Bitcoin transactions (January 2009 – September 2017)
- wikimedia.org
The first blockchain was conceptualized by a person (or group of people) known as Satoshi Nakamoto in 2008. Nakamoto improved the design in an important way using a Hashcash-like method to add blocks to the chain without requiring them to be signed by a trusted party.
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# Sections
# See also
- Scalable privacy for every blockchain - enigma.co