I Have a Question

I thought they were ones sent from a bird's home.....

i think they are replies that respond to a persons comment within a question

It's like replying to someone specifically and directly

I didn't know what it was until I read this.

Thanks for the answers, but I'm still not clear as to what they are, maybe a Moderator can explain?
Cue the cliched "magical chimes" as someone looking from above gives us the answer 😃😃😃

Instead of 64 different replied,you get 1 notification that 64 people replied on a story.