What are micro-interactions

Microinteractions are the satisfying little details in performing a single task, which can be summarized as acknowledgment.

The micro-interactions can be broken down into four components:

Trigger, which is the event starting the microinteraction.
Manual: by interacting with product intentionally
Automatic: when certain conditions meet
Rules. Parameters the microinteraction follows.
Feedback. Verification of microinteraction, where the users receive the acknowledge.
Loops/Modes. Determine the length of the microinteraction.

Feedback is the most important component since:

It assures users what is happening
It delight users with something unexpected.
It can create memorable instances for the brand. Like the "like" button of Facebook