Springs for people who don't do physics

A spring has a stiffness, which is how hard it pulls toward where it is going, and a damping, which is how much it resists moving at all. There is a mass too, but leave it at 1: changing it only does what the other two already do.

To tune one, raise stiffness until the motion is as quick as you want, then raise damping until it stops wobbling more than you want. That is the whole method, and it works because the two numbers mostly do separate jobs.

Almost everything I ship uses one of two springs. A snappy one, stiff and well damped, for presses, toggles and indicators: it arrives fast and doesn't overshoot. A smooth one, slower and with no bounce at all, for panels, sheets and anything that changes size.

A third, bouncy spring is for the rare moment that should feel playful. Reach for it more than once a screen and it stops being playful.