My 5 month old waves her hands back and forth in front of her face and likes to sucks on her fist. Why?

My baby is fascinated with her hands and fingers at 6 months. She often stops to admire her fingers and can be entertained for quite a long time! It's part of normal development where they are starting to understand their bodies and movement. Sucking is a very natural instinct for babies, that's why they often use their fist or thumb in place of a nipple.