The "mirror stage" is a concept introduced by the psychoanalyst Jacques Lacan. It describes a developmental phase in infants, typically occurring between 6 to 18 months of age. During this stage, a child first recognizes their own reflection in a mirror, leading to a sense of self-awareness and identity. This recognition is crucial for the formation of the ego. In the mirror stage, the child experiences a sense of wholeness and unity when seeing their image, which contrasts with their actual feelings of fragmentation and dependency. This moment marks a significant step in psychological development, influencing how individuals perceive themselves and relate to others throughout their lives.