Blockchain is a peer-to-peer network system that uses technologies such as cryptography and consensus mechanisms to create and store a large chain of blocks of transaction information.
Each block contains the cryptographic hash of the previous block, the corresponding time stamp, and the transaction information, which makes the block content difficult to tamper with. A distributed ledger linked by blockchain technology allows two parties to effectively record a transaction and have permanent access to that transaction.
The largest application of blockchain technology is currently the invention of digital currencies, such as Bitcoin. Because the essence of payment is "adding a reduced amount from account A to account B". If one has a public ledger of all the transactions of all the accounts so far, then for any account one can calculate the amount of money it currently has. The blockchain is precisely the public ledger used for this purpose, and it keeps a record of all transactions. In the Bitcoin system, a Bitcoin address is equivalent to an account, and the number of Bitcoins is equivalent to the amount of money.
Blockchain originated from Bitcoin. Satoshi Nakamoto proposed the concept of "blockchain" in 2008 in "Bitcoin: A Peer-to-Peer Electronic Cash System", describing the concept of electronic cash system based on P2P network technology, cryptography, timestamp technology, blockchain technology, etc. On January 3, 2009, the first On January 3, 2009, the first creation block with a serial number of 0 was created, the "Genesis Block", which marked the birth of Bitcoin. A few days later, on January 9, 2009, a block with a serial number of 1 appeared and was connected to the Genesis block with a serial number of 0 to form a chain, marking the birth of the blockchain.