the hinge point

A hinge point is a specific location on a structure where movement or rotation occurs, similar to a door hinge. In broader contexts, it can refer to a critical point on an object, system, or curve where a significant change or pivot happens. For example, in architecture, it's where two parts of a building connect to allow movement. In transportation or mechanics, it denotes a joint enabling rotation. Essentially, a hinge point is the key spot that allows parts to flex, turn, or shift, facilitating function or change in the overall system.