Head injuries are one of the most common causes of disability and death in adults. The injury can be as mild as a bump, bruise (contusion), or cut on the head, or can be moderate to severe in nature due to a concussion, deep cut or open wound, fractured skull bone(s), or from internal bleeding and damage to the brain. A head injury is a broad term that describes a vast array of injuries that occur to the scalp, skull, brain, and underlying tissue and blood vessels in the head. Head injuries are also commonly referred to as brain injury, or traumatic brain injury (TBI), depending on the extent of the head trauma. Head injuries are rising dramatically--about 1.7 million people have a TBI each year. Millions of Americans are alive today who have had a head injury and now need help with the activities of daily living, costing the country more than $56 billion per year. Head injuries are injuries to the scalp, skull, or brain caused by trauma. Concussions are the most common type of sports-related brain injury with an estimated 1.6 million to 3.8 million sports-related concussions a year. A concussion is a type of traumatic brain injury (TBI) that happens when the brain is jarred or shaken hard enough to bounce against the skull. This can happen when two athletes collide or when someone falls and hits his or her head. It can also result from being hit in the head with a piece of sporting equipment. In a sport such as soccer, even "heading" the ball can cause a concussion. A concussion causes an alteration of a person's mental status and can disrupt the normal functioning of the brain. Multiple concussions can have a long-lasting, cumulative life-changing effect.