In one sentence, describe what the following article is about:

Not everyone who gets a concussion will lose consciousness, but some people do. This is the most obvious sign that someone has a concussion. If the person has blacked out after a blow to the head, seek emergency medical treatment. Ask the person some basic questions such as, “What is your name?” and “Do you know where you are?” If their answers are delayed, slurred, don’t make sense, or are hard to understand, they may have a concussion. If the person has a blank stare, seems confused, or doesn’t know where they are, it could be a sign of a brain injury. If they seem dazed, don’t remember what happened, or appear to have memory loss, they likely have a concussion. If someone vomits, especially repeatedly, after being hit in the head or involved in another type of accident, this usually indicates a concussion. If they haven’t vomited, ask them if they feel nauseated or have an upset stomach, which may also be a sign of a concussion. People with concussions often have problems with their motor skills, such as being unable to walk in a straight line or catch a ball. If the person is having trouble with these things or has a delayed reaction time, they likely have a concussion. A headache that lasts more than a few minutes is a common sign of a concussion. Blurred vision, “seeing stars,” and/or feelings of dizziness or fogginess may also indicate a concussion. If you suspect a concussion, the person should be carefully monitored for the next several hours. It’s not a good idea to leave them alone, in case they end up needing emergency medical treatment. If possible, arrange for someone to stay with the person for at least a few hours after the incident and monitor their behavior.

Summary:
Determine if the victim has lost consciousness. Watch for slurred or unclear speech. Find out if the victim is confused or doesn’t remember what happened. Watch for nausea or vomiting. Look for impaired balance or coordination. Ask the victim if they have a headache, blurred vision, or feel dizzy. Watch the person carefully for 3-4 hours.