Five calm reactions sit under a post or reply: helpful, love it, congrats, insightful and watching. Use one instead of a plus-one reply.

Mentions#

Type @ and a handle, for example @ann. The person gets a notification. Mention someone who can help, not a crowd.

What notifies you#

Replies to your posts, mentions, accepted answers and announcements of the sides you joined. Moderation actions that concern you arrive there too. The count shows in the menu.