Violence is defined by the World Health Organization as "the intentional use of physical force or power, threatened or actual, against oneself, another person, or against a group or community, which either results in or has a high likelihood of resulting in injury, death, psychological harm, maldevelopment, or deprivation", although the group acknowledges that the inclusion of "the use of power" in its definition expands on the conventional understanding of the word. This definition involves intentionality with the committing of the act itself, irrespective of the outcome it produces. However, generally, anything that is excited in an injurious or damaging way may be described as violent even if not meant to be violence (by a person and against a person).
Globally, violence resulted in the deaths of an estimated 1.28 million people in 2013 up from 1.13 million in 1990. Of the deaths in 2013, roughly 842,000 were attributed to self-harm (suicide), 405,000 to interpersonal violence, and 31,000 to collective violence (war) and legal intervention. In Africa, out of every 100,000 people, each year an estimated 60.9 die a violent death. Corlin, past president of the American Medical Association said: "The United States leads the world—in the rate at which its children die from firearms." He concluded: "Gun violence is a threat to the public health of our country." For each single death due to violence, there are dozens of hospitalizations, hundreds of emergency department visits, and thousands of doctors' appointments. Furthermore, violence often has lifelong consequences for physical and mental health and social functioning and can slow economic and social development.
In 2013, assault by firearm was the leading cause of death due to interpersonal violence, with 180,000 such deaths estimated to have occurred. The same year, assault by sharp object resulted in roughly 114,000 deaths, with a remaining 110,000 deaths from personal violence being attributed to other causes.
Violence in many forms is preventable. There is a strong relationship between levels of violence and modifiable factors such as concentrated poverty, income and gender inequality, the harmful use of alcohol, and the absence of safe, stable, and nurturing relationships between children and parents. Strategies addressing the underlying causes of violence can be effective in preventing violence.