In the United States, the Centers for Disease Control and Prevention (CDC) uses the term child maltreatment to refer to both acts of commission (abuse), which include "words or overt actions that cause harm, potential harm, or threat of harm to a child", and acts of omission (neglect), meaning "the failure to provide for a childs basic physical, emotional, or educational needs or to protect a child from harm or potential harm". : 11  The United States federal Child Abuse Prevention and Treatment Act defines child abuse and neglect as, at minimum, "any recent act or failure to act on the part of a parent or caretaker which results in death, serious physical or emotional harm, sexual abuse or exploitation" or "an act or failure to act which presents an imminent risk of serious harm". Forms of abuse
As of 2006, the World Health Organization distinguishes four types of child maltreatment: physical abuse; sexual abuse; emotional (or psychological) abuse; and neglect. Physical abuse
Among professionals and the general public, there is disagreement as to what behaviors constitute physical abuse of a child. Physical abuse often does not occur in isolation but as part of a constellation of behaviors including authoritarian control, anxiety-provoking behavior, and a lack of parental warmth. The WHO defines physical abuse as:

Intentional use of physical force against the child that results in – or has a high likelihood of resulting in – harm for the childs health, survival, development, or dignity. This includes hitting, beating, kicking, shaking, biting, strangling, scalding, burning, poisoning, and suffocating.
Child abuse and neglect have been shown, in some cases, to cause important regions of the brain to fail to form or grow properly, resulting in impaired development. Structural brain changes as a result of child abuse or neglect include overall smaller brain volume, hippocampal atrophy, prefrontal cortex dysfunction, decreased corpus callosum density, and delays in the myelination of synapses. These alterations in brain maturation have long-term consequences for cognitive, language, and academic abilities. In addition, these neurological changes impact the amygdala and hypothalamic-pituitary-adrenal (HPA) axis which are involved in stress response and may cause PTSD symptoms. Poor physical health. In addition to possible immediate adverse physical effects, household dysfunction and childhood maltreatment are strongly associated with many chronic physical and psychological effects, including subsequent ill-health in childhood, adolescence and adulthood, with  higher rates of chronic conditions, high-risk health behaviors and shortened lifespan. Adults who experienced abuse or neglect during childhood are more likely to have physical ailments such as allergies, arthritis, asthma, bronchitis, high blood pressure, and ulcers. There may be a higher risk of developing cancer later in life, as well as possible immune dysfunction. Exposure to violence during childhood is associated with shortened telomeres and with reduced telomerase activity. The increased rate of telomere length reduction correlates to a reduction in lifespan of 7 to 15 years.