A three-year-old is a child who is typically between 36 and 47 months old. At this age, children are developing rapidly in various areas, including language, motor skills, and social interactions. They often begin to form simple sentences and can express their needs and feelings more clearly. Three-year-olds are also known for their curiosity and energy. They enjoy exploring their environment, engaging in imaginative play, and learning through hands-on activities. This stage is crucial for developing foundational skills that will support their growth in areas like preschool and later in kindergarten.