Dan Saffer structured these in his 2013 book "Microinteractions" as trigger → rules → feedback → loops/modes. A toggle flip, pull-to-refresh, or a save checkmark are all microinteractions.
The point: functionally optional, but they confirm the action happened and add a moment of delight. Tap a button with zero response and users aren't sure it registered — so they tap again (hello, duplicate requests).
Watch the heart: it scales up, fills with colour, and throws small particles — that's feedback. The rising count is the rule's result.
When to use
Design these for small, frequent actions — like, save, toggle, delete. Keep them under 200–400ms or they start to feel distracting.