what's the div and div class used for?

Answer 1

Dividing different segments of your output for editing, customization or just a cleaner, less cluttered look.

Keep in mind that it's a block level element.
It can be replaced with "<span></span>" if you want to use it inline.

Answer 2

https://www.sololearn.com/discuss/454922/?ref=app
https://www.sololearn.com/discuss/408473/?ref=app
https://www.sololearn.com/discuss/413214/?ref=app
https://www.sololearn.com/discuss/405358/?ref=app
https://www.sololearn.com/discuss/423552/?ref=app
https://www.sololearn.com/discuss/382712/?ref=app
https://www.sololearn.com/discuss/108567/?ref=app

and so on.........