We’re always testing ways to make Messenger more fun and engaging. This is a small test where we enable people to share an emoji that best represents their feelings on a message.
According to Constine, users who are part of the test group can hover over messages from friends to bring up the emoji menu, and uses of those emoji are tallied in a counter. Users can also view a list of which friends used which emoji.
Facebook launched Reactions for its flagship apps and desktop site Feb. 24, 2016, and it said this past Feb. 24 that the feature had been used more than 300 billion times during its first year of availability.