I read a blog post about bleeding in brain. but i'm still not clear - what is it?

Different types: There are several types of hemorrhage: subarachnoid, subdural, epidural, intracerebral, cerebellar, brainstem and a few others primarily based on location and the reason for the hemorrhage. Reasons for hemorrhage are high blood pressure, trauma, aneurysm, arteriovenous malformation, idiopathic- we don't know why, tumor, infection, and others.

As it states: The brain is a very vascular organ with many veins and arteries. Bleeding inside or around the brain can be from: blunt or penetrating trauma(shearing of vessels) , very high or untreated high blood pressure, localized breakdown of vessel walls after a stroke, leaking aneurysms, congenital vessel malformations, brain tumors. These all have varied presentations.