the.com/stair
A machine for converting laziness into cardio, one reluctant step at a time.
means A single step, or a set of steps, that lets you move between different levels of a building.
from From Old English 'stǣger,' which traces back to a Germanic root meaning 'to climb' or 'to ascend' — the same family that gives us 'sty' (as in a swelling that 'rises' on the eyelid). The word literally carries the idea of climbing built into its bones, so every staircase has been quietly about ascent since long before English had its name.
escalator originEscalator was a trademarked brand before becoming generic.
falls tollStairs cause over a million injuries yearly in America.
penrose trickImpossible stairs climb forever yet go nowhere.
odd numbersOld builders made step counts odd for luck.