A lumbar puncture, also known as a spinal tap, is a medical procedure used to collect cerebrospinal fluid (CSF) from the lower back. This fluid surrounds the brain and spinal cord, providing important information about conditions like infections, bleeding, or neurological disorders. During the procedure, a doctor inserts a thin needle between the vertebrae in the lower back to access the CSF. The procedure is typically performed in a hospital or clinic and may be done under local anesthesia to minimize discomfort. Patients may feel pressure or a brief sting, but serious complications are rare. Results from the CSF analysis can help diagnose conditions such as meningitis or multiple sclerosis.