So what does it mean when a baby giggles?

Today, Cailee audibly giggled and got a wide grin with dimples and all. She smiles quite often and I just want to believe that its so much more than gas (although she has her fair share of that as well). I am most certainly biased but I have to believe that she’s a happy baby and seems very content in her surroundings. Now what prompted the giggle, I have no idea – but I hope it becomes a regular habit.