What Is the Significance of the “Block Height” in the Context of the Longest Chain Rule?

The block height is the number of blocks preceding a specific block in the blockchain, representing its position in the chain. In the context of the longest chain rule, a higher block height signifies a longer chain, which has accumulated more Proof-of-Work.

The network's consensus mechanism always selects the chain with the greatest cumulative work, and this is typically identified by the highest block height. Thus, the block height is a simple proxy for the chain's validity and security.