Teaching your child ways to understand the feelings associated with anger and express these emotions in a construtive not destructive manner is the best way to deal with their anger outbursts.
As well as your child's physical development and changes in the growth of their brain, there are many common situations and feelings that can trigger an anger episode.
When children are upset or can’t get what they want, they tend to have a general temper tantrum, it is all part of them growing up & testing boundaries.
ADHD (Attention-Deficit Hyperactivity Disorder) is related to impulsive & hyperactive behaviour & is mainly diagnosed in children, though this can be problematic for many adults too.