Users can choose from seven emotions, which are very similar to Facebook's feature on Messenger.
They range from emojis depicting laughter, shock and sadness to a heart, a flame, a thumbs up and a thumbs down.
The feature can be applied by hovering over any message received and selecting a heart plus icon that appears.
People can also choose to undo the reaction at any time.
Reaction emojis work across desktop, iOS and Android.