Discuss topics in threads
Threads are replies to messages. They help keep chats and channels organized so that important messages don't get lost in discussions.
To leave the first reply, select the message and press Discuss

Follow important threads
If you want to stay updated on what's being discussed in a thread, open the thread and press
You'll also automatically follow a thread if:
- You have added a reply within the thread.
- You've marked a message from the thread as important or unread.
- You've been mentioned in a thread message.
To see all the threads you're following, press Chats at the bottom of the screen, then go to Threads. To unfollow a thread, open it and press

Manage threads in channels and chats
As an admin of a group chat or channel, you can permit or forbid users to communicate in threads. If the Chat in threads option is disabled in settings, only chat and channel admins can comment on posts.