Infants are defined as children from birth to 12 months old. During this time, infants are learning about their world through their senses and interactions. Their movements start as reflexes but develop into purposeful activities like grasping, rolling over, and sitting with support. By one year old, most infants can sit alone, crawl, pull themselves up, walk when led, and weigh three times their birth weight. Infants need a safe environment to explore with responsive adults who recognize and meet their individual needs through consistent nurturing care, routines, play, and social interaction.