The most common type of serious accident in the modern world. Although rates of the incidence of automobile accidents have steadily decreased for decades, the mass and speed of an automobile combined with many U.S. citizens driving on a daily basis means that often people's lives are touched in large or small ways by car accidents. A traffic collision, also known as a traffic accident, motor vehicle collision, motor vehicle accident, car accident, automobile accident, road traffic collision, road traffic accident, wreck (USA), car crash, or car smash (Australian) occurs when a vehicle collides with another vehicle, pedestrian, animal, road debris, or other stationary obstruction, such as a tree or utility pole. Traffic collisions may result in injury, death, vehicle damage, and property damage. A number of factors contribute to the risk of collision, including vehicle design, speed of operation, road design, road environment, driver skill and/or impairment, and driver behavior. Worldwide, motor vehicle collisions lead to death and disability as well as financial costs to both society and the individuals involved. Traffic collisions can be classified by general type. Types of collision include head-on, road departure, rear-end, side collisions, and rollovers. Many different terms are commonly used to describe vehicle collisions. The World Health Organization use the term road traffic injury, while the U.S. Census Bureau uses the term motor vehicle accidents (MVA), and Transport Canada uses the term "motor vehicle traffic collision" (MVTC). Other terms that are commonly used include auto accident, car accident, car crash, car smash, car wreck, motor vehicle collision (MVC), personal injury collision (PIC), road accident, road traffic accident (RTA), road traffic collision (RTC), road traffic incident (RTI), road traffic accident and later road traffic collision, as well as more unofficial terms including smash-up, pile-up, and fender bender. Some organizations have begun to avoid the term "accident". Although auto collisions are rare in terms of the number of vehicles on the road and the distance they travel, addressing the contributing factors can reduce their likelihood. For example, proper signage can decrease driver error and thereby reduce crash frequency by a third or more. That is why these organizations prefer the term "collision" rather than "accident". However, treating collisions as anything other than "accidents" has been criticized for holding back safety improvements, because a culture of blame may discourage the involved parties from fully disclosing the facts, and thus frustrate attempts to address the real root causes. Vehicle Accident Information at Nolo