Age appropriateness refers to people behaving as predicted by their perspective timetable of development. The perspective timetable is embedded throughout people's social life, primarily based on socially-agreed age expectations and age norms. For a given behavior, such as marrying, entering school, etc., there are years within which the behavior is regarded appropriate. By contrast, if the behavior falls out of the age range, it will be considered age-inappropriate. Most people are adhered to these age norms and are aware of whether their timing is "early," "delayed," or "on time."
Age appropriateness is considered essential for children's skills development. Children's motor, cognitive and social skills are formed through several development stages. Looking at a child's functional development involves observing whether or not the child has mastered certain developmental milestones and expectations for his or her age. Lack of exposure to age-appropriate activities and experiences in a specific stage is thought to prevent a child from gaining the skills necessary for their current and thus their next stage of development.
There are various sanctions associated with age inappropriateness, ranging from social isolation, damage to physical health and cognitive development, and forming of improper behaviour.