Dissecting a block

A block is formed by combining a list of transactions with a header. As depicted in the flow diagram in Figure 2.7, when transactions are added to a block, they alter the state of the blockchain:

Figure 2.7 – How a blockchain evolves (adapted from https://ethereum.org/en/developers/docs/blocks)

The preceding diagram illustrates the progressive evolution of blockchain state data, one block at a time. Blocks are strictly ordered, allowing us to trace the history of each state variation.

In the Ethereum Yellow Paper, a block is defined as “the collection of relevant pieces of information (known as block header) [...], together with information corresponding to the comprised transactions, [...] and a set of other block headers [...] that are known to have a parent equal to the present’s block’s parent (such blocks are known as ommers).”

Therefore, a block consists of three main components:

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