My 3 month old baby seems to always be laughing. What is she laughing about? Does she already have a sense of humor?

Your baby has been experimenting with making sounds and laughter is her next step in learning to communicate. Baby's first laugh might be inspired by something as simple as seeing a favorite toy, pet or person (mummy and daddy). Once baby has discovered how to laugh, she may laugh just because laughing feels good, and it's such a fun new sound to make. Plus, with each coo and goo she's learning and practicing how to move her mouth and tongue to produce different sound effects. I would say, enjoy these moments.