An intracranial hemorrhage is bleeding in the brain. ("Intracranial" means "inside the skull"; "hemorrhage" means "dangerous bleeding"). The most dangerous type of stroke, a hemorrhagic stroke, is a type of intracranial hemorrhage. It is a bleed in the brain that happens when the brain has not been injured.
When blood vessels in the brain break or are injured, they bleed. Bleeding in the brain is very dangerous, because if enough blood builds up, the blood can squeeze or crush the brain. It can also make it impossible for oxygen to get past the blood to parts of the brain. Without oxygen, these parts of the brain will die.