Block height refers to the number of blocks preceding a particular block in the Bitcoin blockchain. The genesis block (the first Bitcoin block mined by Satoshi Nakamoto in 2009) has a block height of 0. Each subsequent block increases the height by one, meaning the latest block’s height indicates its position in the chain.

Block height is crucial for:

Tracking Blockchain Progress – It helps nodes and users verify how far the blockchain has progressed.

Confirmations – A transaction’s security increases with each new block added on top of it (e.g., 6 confirmations mean 6 blocks mined after the block containing the transaction).

Network Synchronisation – Nodes compare block heights to ensure they are on the correct chain.

Halving Events – Bitcoin’s block reward halves every 210,000 blocks (roughly every 4 years), and block height helps predict these events.

Unlike block hashes (which are unique identifiers), block height is a simple sequential count. However, in rare cases of chain reorganisations, a block at a certain height may change if a competing chain becomes longer.

In summary, block height is a fundamental metric for understanding Bitcoin’s growth, security, and economic events like halvings.