What is cerebrospinal fluid? What is its function?

(N/A) Cerebrospinal fluid $(CSF)$ is a clear,colorless body fluid found in the brain and spinal cord.
It occupies the subarachnoid space and the ventricular system around and inside the brain and spinal cord.
Function: It acts as a cushion or shock absorber,protecting the brain and spinal cord from mechanical injury and sudden impacts.