At 9—12 months it is absolutely normal for children not to play with others yet.In this phase of growth, the game is mostly individual or shared with the reference adults: it serves to explore the body, objects and first emotions.When he is close to other children, he can look at them, smile, imitate some gesture, but not yet share the game in the sense of exchanges or cooperation.Socialization does not begin only when children play together, but much earlier: - when they observe others with curiosity; - when they smile or they vocalize to attract attention; - when they seek the adult's gaze to understand if a situation is safe or pleasant; - when they imitate a gesture or a laugh. These are the first basics of social behavior: the child learns to read emotions, to understand that there are 'others' around him, and that he can enter into a relationship.