A concussion is a traumatic brain injury (TBI). It can vary in severity from mild to serious. It occurs after an impact to your head or after a whiplash-type injury that causes your head and brain to shake quickly back and forth.
A concussion results in an altered mental state with a variety of signs and symptoms. 

Below are links to aid in better understanding concussions as well as resources designed to facilitate the assessment and treatment of concussions particularly in the area of sports. Many of these resources are based on the guidelines utilised in the management of concussions in Rugby Union. Rugby, as a sport, has long been at the forefront of concussion discussions and management.