Exploring the Basics of Blockchain: Block Structure and Chain Overview

Blockchain, the foundation of Bitcoin, introduced in 2008 and operationalized in 2009, functions as a public ledger where all confirmed transactions are permanently stored in a sequential list of blocks. This chain steadily expands as new blocks are added. Importantly, blockchain exhibits immutability, ensuring transactions remain unaltered once incorporated into the blockchain (Zheng et al., 2017).

Figure 1: Blockchain architecture (Zheng et al., 2017, pp. 558).

Figure 2: Structure of one block (Zheng et al., 2017, pp. 558).

Each block comprises two essential components: the block header and the block body. The block header encompasses:

-      Block Version: specifies the set of block validation rules to adhere to

-      Merkle Tree Root Hash: the hash value representing all transactions within the block

-      Timestamp: reflects the current time in seconds using universal time

-      nBits: defined the target threshold for a valid block hash

-      Nonce: a 4-byte field initiating with 0, incrementing with each hash calculation

-      Parent Block Hash: a 256-bit hash value pointing to the preceding block

The block body consists of a transaction counter and the actual transactions. This dual structure ensures the integrity and security of the blockchain, with the block header playing a crucial role in validating and linking consecutive blocks (Zheng et al., 2017).

References:

Zheng et al. (2017). An Overview of Blockchain

Technology: Architecture, Consensus, and Future Trends. IEEE 6th International Congress

on Big Data. https://doi.org/10.1109/bigdatacongress.2017.85