A concussion is an injury to the brain that is caused by a sudden, abrupt movement of the head, typically because of a blow or jolt to the head or body that makes the brain move rapidly inside the skull.
The injury that results from this is called a mild traumatic brain injury, most commonly referred to as a concussion. There are many different definitions of concussion, but they all have some things in common. These common features include changes in brain function, including changes in the way you think (cognitive changes), in the way your brain works (neurological changes), and in the way you feel (physical and emotional changes). These changes may or may not be accompanied by a temporary loss of consciousness, also known as fainting or passing out. The abrupt movement of the brain can stretch and injure brain cells, which can change the way these cells function. These changes can be short-lived or long-lived, but most of the time, the cells heal and function normally in 7–10 days.
Sometimes, it may take longer than 10 days for the brain to return to normal after a concussion, especially in children.

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