How data is written to a blockchain model?

Blockchains are write-only data structures with no adminis- trative permissions for editing or deleting of the data . The data structures are known as blocks and are distributed in a P2P network. Each block contains the cryptographic hash function of the previous block and is used to develop a link between them.

Blockchain does not store any of its information in a central location . Instead, the blockchain is copied and spread across a network of computers. Whenever a new block is added to the blockchain, every computer on the network updates its blockchain to reflect the change.

Merkle Trees . Each block in the bitcoin blockchain contains a summary of all the transactions in the block, using a merkle tree. A merkle tree, also known as a binary hash tree, is a data structure used for efficiently summarizing and verifying the integrity of large sets of data.