"Exist" refers to the concept of something being present or real, regardless of whether it is currently being observed. In cognitive development theory, it specifically relates to a child's understanding that objects continue to exist even when they are not able to see them.
Related terms
Object Permanence: This term refers to a specific cognitive milestone in which a child understands that objects continue to exist even when they are out of sight.
Sensorimotor Stage: According to Piaget's stages of cognitive development, this is the first stage where object permanence develops. It occurs from birth until around 2 years old.
Conservation: Conservation refers to the understanding that certain properties of an object remain constant even when its appearance changes. It is another important concept in cognitive development.