Just brackets, what is it for?

Sometimes I see people use single brackets, sometimes two or three after a sentence, what is it for?

Like this )

OR Thanks! )))

OR Congrats!))

Is it a smiley, just a habit, or something else? I ask because I see this a lot on this forum and I’m curious

Weird. I haven’t seen this anywhere. A mistyped smiley, I would suppose!

This is a smiley. A lot of teenagers uses them.

You know you’re getting old when there’s yet another kind of smiley you haven’t seen before… ))

Weird. I’m 17, please don’t get any ideas of oldness

Yes, this is a smiley))

You guys still haven’t told me what this smiley is for

I tried searching the web but I get nothing except for endless smiley lists with no smileys that are just brackets in sight

)) = :)) .... ) = ... I think so xD !

I use it as a big smile))

It’s some secret code of a secret global society. I can’t tell you more ‘cause it’s a secret.