Notes

In the blockchain all transactions are recorded in chronological order as a sequential list of transactions in the block chain, called the blockchain ledger. In the blockchain, by design, it is very difficult, with current technology, to attempt to reverse a transaction. Because the blocks are linked in chronological order, and each block can be verified independently, it is impossible to delete the records of transactions that took place ever. It is like trying to delete comments from a website.

As of August 2018, the blockchain had produced more than 100 million unique bitcoins.

Content of a block

A block typically contains:
A hash of the previous block (called the merkle root)
A link to the previous block in the chain
An indicator that this is a "valid" block (i.e. valid proof of work)
A timestamp to the nearest second
A hash of the block header
A 16 byte merkle root of the block's contents
A script that allows the receiver of the block to prove that he has spent this block's bitcoin output (see proof of work)
A script that allows the receiver of the block to prove that he received this block's bitcoin input

Merkle tree

In order to protect the buyer of a product or service from the seller, a secret cryptographic technique, the Merkle root, is used. The seller uses a cryptographic function of the Merkle root to scramble the product or service and uploads the scrambled product or service to the blockchain as a transaction output. Then, the buyer uses a cryptographic function of the Merkle root to unscramble the product or service at the point of purchase and signs the unscrambled product or service with his private key. This signature proves to the seller that the purchase was authorized.

The Merkle root,, is a cryptographic hash function of the previous block's contents:

Block ID

Each block contains a 32-byte hash of its header, the block id, which serves as a version identifier for the current version of the blockchain. A given timestamp is associated with the block having the highest block ID, as seen in the nt timestamp element. https://vayonline24h7.vn/ The block ID is a modular 64-bit number, where the lowest 32 bits form an unsigned integer to identify the block's version, and the highest 32 bits are a network-specific part of the timestamp.

Transactions

Each block contains a variable-length list of transactions contained within it. A
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