Play is one of the most important activities of a child by which he meets new people, develops friendly relations, learns how to regulate his own emotions and develops motor skills. Through play a child acquires different knowledge, abilities and skills, social, emotional, physical and cognitive abilities, and the period of childhood is considered the most important period for play. The aim of this final paper is to describe and explain the role and importance of play for the development of the child's entire personality. The paper consists of two parts. The first part of the paper discusses definitions, characteristics, theories (personality theory, cognitive, sociocultural, interaction theory and socialization theory) and types (functional, symbolic game, game according to rules and video games) of games. The second part discusses play in preschool and school age, through several topics such as the importance of free play, play in Montessori pedagogy, Floor-time approach as one of the play therapies and research on children's experience of play depending on preschool and school age. Finally, we talk about play and personality traits through cognitive, emotional, physical, and social development.