At what age do children typically start to show defiant behavior and play besides other kids?

Children typically start to exhibit defiant behavior and engage in parallel play around the age of 2 years. At this stage of development, toddlers are beginning to assert their independence and express their own preferences, often resulting in defiance or oppositional behavior when faced with rules or requests from caregivers. Parallel play, where children play alongside but not directly with each other, is common at this age as they become more socially aware but are still developing the skills necessary for cooperative play. This behavior is a natural part of their growth as they explore their boundaries and social interactions. By the time they reach age 3, children begin to engage in more interactive play with peers, which reflects further advancement in their social and emotional development.