Hover over the message bubble, or tap and hold on a phone, and a small row of buttons appears beside it. The smiley face opens a picker with five emoji: 👍, ❤️, 🎉, 😄 and 🙏. Choose one and it attaches to the message as a chip underneath.
The controls are hidden until you hover on purpose, which is why most people never find them.
One reaction each, and it swaps
You get one reaction per message. Picking a second emoji does not add it, it replaces the first. There is no unreact then react dance to perform: choose the one you want and it takes over.
To take yours off entirely, click your own chip. Chips you have reacted to are marked as yours.
A chip is a count, not one person's reaction. Clicking someone else's chip joins it and the number goes up, exactly as if you had picked that emoji from the picker.
Reacting marks the message read
This is the part that surprises people. Reacting to a message marks it as read, on the reasonable ground that you clearly saw it. The unread badge on your conversation clears, and the person who sent it sees their message move to Read. See read receipts and the online dot.
So a reaction is not a quiet way to acknowledge something without letting on that you have seen it. It is the opposite: it is the most explicit way of saying you have.
Where it is useful
A reaction closes a conversation without forcing a reply that means nothing. When someone signs off with "thanks for the help", a 🙏 says it landed. It is also how the UNI team acknowledges a support thread that has reached its end, so a reaction from us is not us ignoring you, it is us confirming there is nothing left to answer.
Two things you cannot react to
- A deleted message. Once a message is deleted the buttons are gone from it.
- Anything from someone who has blocked you. A reaction is something you push into another person's thread, so a block closes it in the same way it closes messages. Removing a reaction you had already left is still allowed. See deleting messages and blocking someone.
You can react to your own messages. Nothing stops you and it costs nothing, though nobody is notified by it.