Glioblastoma, also known as glioblastoma multiforme (GBM), is a highly aggressive type of brain tumor that originates from the glial cells in the brain. These tumors are known for their rapid growth and their ability to invade nearby brain tissue, making them particularly challenging to treat. Glioblastoma is classified as a grade IV astrocytoma by the World Health Organization (WHO), indicating its high malignancy.