Infants are very young children, typically defined as those from birth to one year old. During this stage, they undergo rapid physical and cognitive development. Infants rely on caregivers for basic needs such as feeding, diaper changes, and comfort. They communicate primarily through crying and begin to develop social skills by responding to voices and faces. In their first year, infants experience significant milestones, including rolling over, sitting up, and starting to crawl. They also begin to explore their environment and may show preferences for certain toys or people. This period is crucial for brain development, as infants learn through sensory experiences and interactions with their surroundings.