The primary substance that protects the brain and spinal cord is cerebrospinal fluid (CSF). CSF acts as a shock absorber, cushioning these vital structures from physical trauma. Additionally, it provides a vital environment for the brain, delivering essential nutrients and removing waste products. The presence of cerebrospinal fluid is crucial in maintaining homeostasis within the central nervous system. Studying CSF helps in understanding various neurological conditions and diseases, guiding diagnostic and treatment approaches.