Understanding the grid classes ( col-sm-# and col-lg-# ) in Bootstrap 3

Question

I\'m getting started on Bootstrap 3 and I\'m having some trouble understanding how the grid classes are meant to be used.

Here\'s what I\'ve figured out so far:

Answer 1

"If I want two columns for anything over 768px, should I apply both classes?"

This should be as simple as:

No need to add the col-lg-6 too.

Demo: http://www.bootply.com/73119