A spinal tap, also known as a lumbar puncture, is a medical procedure used to collect cerebrospinal fluid (CSF) from the spinal canal. This fluid surrounds the brain and spinal cord, providing protection and nourishment. The procedure involves inserting a thin needle into the lower back, typically between the lumbar vertebrae, to access the CSF for testing. Doctors may perform a spinal tap to diagnose conditions such as meningitis, multiple sclerosis, or bleeding in the brain. It can also be used to administer medications or relieve pressure in the spinal canal. The procedure is generally safe, though some risks include headache or infection.