The Sensorimotor Stage is the first of the four stages in Jean Piaget's theory of cognitive development, occurring from birth to about 2 years old. During this stage, infants learn about the world through their senses and actions. They explore their environment by touching, looking, and manipulating objects, which helps them develop basic motor skills and sensory awareness. In the Sensorimotor Stage, infants also develop object permanence, the understanding that objects continue to exist even when they cannot be seen. This cognitive milestone marks a significant shift in their thinking, as they begin to form mental representations of the world around them.