Our school textbook states that base pairs confer stability to the B-DNA double helix in two ways:
1) Hydrogen bonding between purines and pyrimidines of opposite strands.
2) "Stacking of one base-pair plane over the other"
It's the second point that I'm not able to understand. I did try looking it up on the internet, but I'm not able to find anything relevant in that regard.
So could someone please try explaining that second point to me?