A sippy bottle is a reusable bottle designed for toddlers and young children. It has a sippy lid that allows the child to drink easily from the bottle without spilling the contents. Sippy bottles are usually made of plastic and come in a variety of shapes, sizes, and colors. They are often used to help children transition from breastfeeding or using a bottle to drinking from a regular cup. Some sippy bottles have valves that prevent air from entering the bottle when the child is not drinking, which can help to keep the milk or formula fresh.