Definition of blockchain height What is the definition of blockchain height and how is it found/calculated.

I get the idea it is related to the SO answer by Gary Rowe, but the word "height" is not mentioned. Yet I see references to "blockchain height" in many places.
The height of a block is the number of blocks in the chain between it and the genesis block.  (So the genesis block has height 0.)

The height of the block chain is usually taken to be the height of the highest block, in the chain with greatest total difficulty; i.e. the length of the chain minus one.