Definition
Block height is a simple sequential counter that identifies each block’s position in the blockchain. The genesis block (the very first block mined by Satoshi Nakamoto) has a height of 0. Each subsequent block increments by one.
Block height is commonly used to reference specific events: for example, the halving occurs at block heights 210,000, 420,000, 630,000, 840,000, and so on. It is also used for timelocks and other protocol-level features.
In Simple Terms
The position number of a block in the blockchain, starting from zero at the genesis block.
The sequential number of a block in the blockchain, starting from 0 for the genesis block. Block height indicates how many blocks have been mined before it.