Your brain is a soft organ that is surrounded by spinal fluid and protected by your hard skull. Normally, the fluid around your brain acts like a cushion that keeps your brain from banging into your skull. But if your head or your body is hit hard, your brain can crash into your skull and be injured.There are many ways to get a concussion. Some common ways include fights, falls, playground injuries, car crashes, and bike accidents. Concussions can also happen while participating in any sport or activity such as football, boxing, hockey, soccer, skiing, or snowboarding.
via Concussion – WebMD: Causes, Symptoms, Diagnosis, Treatment, and Prevention.