💬 Chat

Chats show a 😃 Smiley emoji when your friend returns to being active.  It looks like this:

smiley-emoji-snapchat-chat

The emoji appears briefly to indicate the recipient has just switched to the current chat:

snapchat-smiley-screenshot

When the 😃 smiley goes away, a blue dot remains to indicate the recipient is still looking at the chat:

snapchat-bluedot-screenshot

When both disappear, your friend has left!