Object permanence is the understanding that objects continue to exist even when they are not visible. This concept is a crucial part of cognitive development in infants, typically developing around 8 to 12 months of age. Before this stage, babies may believe that if they cannot see an object, it has disappeared entirely. The idea of object permanence was first studied by psychologist Jean Piaget. He conducted experiments showing that infants would search for hidden objects once they understood that these objects still existed out of sight. This ability is fundamental for later cognitive skills, such as memory and problem-solving.