Following the footsteps of Facebook, Twitter has added new emoji reactions for Direct Messages, including text and media attachments. Clicking the reaction button that appears when you hover over the message on the web or double-tapping on mobile will show you a pop-up to select an emoji from, the official blog explains. You can undo a reaction and it will be removed from the message for all participants. Any time a new reaction is added to a message, all participants will receive a notification. Those on the older version of the app will see reactions displayed as text-based messages.