system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is buttermilk used in so many cakes and breads, and what separates it from normal milk?
gpt
Buttermilk is slightly acidic.  It reacts with the baking soda to produce carbon dioxide which helps the batter/dough rise.  Think of a vinegar/baking soda volcano.  The acidity also helps break down the proteins (gluten) so the result is less chewy.