It's a dazzling display of gratitude to someone who dazzled you with an awesome answer.
You can thank users with a gift the time an answer wows you.
 

<Sending a gift>

  1. Tap or Click [🎁 Send a gift] under the answer.
  2. Select and Tap or Click the gift.
  3. Tap or Click [Send a gift].
 
※ If you don't have enough coins, you can also charge them when you send a gift.
 

<Receiving a gift>

  1. You receive the notification.
  2. Tap or Click the notification.
  3. Tap or Click [Receive] and [OK].
 
※ You can review the number of gifts received on your profile page.