A brain tumor is an abnormal growth of cells that forms within the brain or surrounding tissues such as the meninges, cranial nerves, or pituitary gland. These cells divide uncontrollably, creating a mass that interferes with normal brain structure and function.
Because the brain is enclosed within the skull, even a small tumor can increase intracranial pressure, disrupt neural communication, and impair vital functions such as movement, speech, memory, and vision. Brain tumors may be non-cancerous (benign) or cancerous (malignant), but both can be dangerous depending on location and growth rate.
Understanding what a brain tumor is forms the foundation for diagnosis, treatment, and technological innovation.