Headache is defined as a pain in the head or upper neck. It is one of the most common locations of pain in the body and has many causes.
There are three major categories of headaches:
Cranial neuralgias, facial pain, and other headaches
Primary headaches include migraine, tension, and cluster headaches, as well as a variety of other less common types of headache. Secondary headaches are those that are due to an underlying structural problem in the head or neck. There are numerous causes of this type of headache ranging from bleeding in the brain, tumor, or meningitis and encephalitis.