The toddler stage is characterized by much growth and change, mood swings and some negativity. Toddlers are long on will and short on skill. This is why they are often frustrated and "misbehave." Some adults call the toddler stage "the terrible twos." Toddlers bursting with energy and ideas need to explore their environment. You need to make sure that they can explore in an environment that is safe for them. They want to be independent, and yet, they are still very dependent. Toddlers are very concerned with their own needs and ideas. This is why we cannot expect them to share. Toddlers sometimes get frustrated because they do not have the language skills to express themselves.
Often they have difficulty separating themselves from their parents. Usually, between 2-1/2 and three years of age, children begin to take an interest in being toilet trained and by age three they are ready to be known as preschoolers. By this age, most children are toilet trained, have developed verbal skills, are continuing to be more independent, and are taking an active interest in the world around them.