Tumor grade

Sometimes Doctors group brain tumors by grade, from low grade (grade I) to high grade (grade IV). From high-grade tumors Cells look more abnormal and usually grow faster than low-grade tumors cells.
Primary brain tumors:

Tumors that start in brain tissues. It is called as primary tumors of the brain. Primary brain tumors are named according to the type of cells or the part of the brain in which they begin. Gliomas is the most common primary brain tumors. They begin in Glial Cells. There are many types of gliomas:

• Astrocytoma. The cancer arises from star-shaped glial cells called Astrocytes. Astrocytomas arise, in adults in the cerebrum. In children, it occur in the brain stem, the cerebrum, and the cerebellum. A grade III astrocytoma is sometimes called an anaplastic astrocytoma. A grade IV astrocytoma is usually called a glioblastoma multiforme.
• Brain stem glioma. This type of  tumor occurs in the lowest part of the brain. Brain stem gliomas most often are diagnosed in middle-aged adults and young children.

The other types of Primary brain tumors are:

Ependymoma Oligodendroglioma Medulloblastoma Meningioma Schwannoma Craniopharyngioma