I love brown sugar! I've started using it in more & more of my cooking & baking. But, yesterday while making my all too awesome meatloaf glaze, I found that my open bag of dark sugary goodness is hard & completely unusable.
Brown sugar gets its brown color from adding molasses to white sugar; it comes in light & dark versions depending on how much molasses is added. It is very yummy & appears in a lot of recipes, but can be really tough to keep light & fluffy.