A headache is typically caused by irritation or inflammation of the blood vessels, muscles, or nerves in the head and neck. It is not a specific part of the brain that is hurt, but rather a result of various factors such as stress, dehydration, or tension. Understanding the underlying cause of a headache can help in finding effective treatment options. In some cases, headaches may be a symptom of a more serious medical condition, so it's important to consult with a healthcare professional for proper diagnosis and management.