Delay
A pause between the trigger and the motion starting. The lever behind staggered lists and tooltips that ignore accidental hovers.
See it
What it is
Delay is dead time inserted between the trigger and the motion starting. On its own it is a blunt instrument, but two uses earn their keep constantly: staggering (give each sibling a slightly larger delay so a list cascades instead of landing as one slab) and intent filtering (a 300 to 500ms delay before a tooltip or mega menu opens means brushing past it triggers nothing).
In CSS it is 'transition-delay' and 'animation-delay'. Negative values are the underused trick: 'animation-delay: -2s' starts the animation two seconds in, which is how you desynchronise a field of identical looping elements without writing a keyframe block for each one.
Gotcha: delay on the way in is charming, delay on the way out is infuriating. Set the exit delay to 0 so dismissing feels instant. And remember delay stacks on top of duration, so a 300ms delay plus a 300ms fade is 600ms before anything looks finished.
Ask AI for it
Add delays deliberately here. Stagger these list items with a 40ms increment per item (index times 40ms, capped so the last item never waits more than 300ms), give the tooltip a 400ms open delay and a 0ms close delay so pointer fly-bys do not fire it, and desynchronise the looping background shapes by giving each a negative animation-delay equal to a random fraction of its own duration. Never put a delay on the exit of anything a user is dismissing.