A toddler's world has no limit until the first negative warning is given. It conveys the idea of prohibition.
Toddlers are naturally inquisitive and want to explore their expanding universe.
They do not understand potential dangers or the parents' restrictions. A toddler's contrariness is out of curiosity, not a desire to frustrate the parents. It is a natural step for developing independence. They may seem contrary, impossible to handle, and constantly opposed to anything parents say or do. This is how they assert their growing independence.