Physical Abuse is by far the most visible form of child maltreatment.
It is often defined as any non-accidental injury.
It can be any physical injury resulting from:
hitting
kickingslapping
shakingpinching
hair pullingchoking
throwingshoving
whippingpunching
beatingbiting
burningpaddling etc.
Yes, it is possible for some of the injuries caused by this type of behavior to occur by accident or playing around, but abuse should be suspected if the explanations do not fit the injury or if there is a pattern of repeated injury. What I mean by this means is that if the same type(s) of injuries continue to occur, then abuse is probable. Also, the existence of several injuries in different stages of healing make it obvious they did not happen as a result of one accident, and the likelihood of the same type of "accident" happening more than once over a short period of time is slim.
A child who is consistently withdrawn, or overly aggressive; one who complains of soreness or wears inappropriate clothing for the weather, or a child who is a chronic runaway may very well be a victim of abuse.
While corporal punishment is not considered child abuse, many child development and child welfare professionals believe that spanking, hitting or slapping is not an effective form of discipline. Once physical methods of discipline are put into practice they can easily escalate into physical abuse if the frequency and severity of the "punishments" are increased.