National Cancer Institute.
Brain cancer is an umbrella term accounting for cancers affecting different tissues in the nervous system. For example, meningioma, the most common brain cancer, forms on the brain’s covering tissue, known as the meninges. Glioma arises in glial cells, the most numerous cells in the brain. The symptoms of a brain tumor can depend on where it manifests - a tumor pressing on the language centers of the brain can compromise speech, for example.
In the MRI scan above, the blue area in the bottom right is a cancerous tumor. Knowing exactly where a cancer is located can help doctors derive the proper treatment for an individual tumor.