Purpose of *:before, *:after rule without content property

Question

From what I understand, :before and :after inserts content before or after the indicated target. I\'m not really sure what would be the purpose of

Answer 1

*, *:before, *:after { box-sizing: border-box; }

This is for not to repeat in all places where you use :after and :before. It automatically adds to all :after and :before.