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 neurological conditions. The procedure involves inserting a thin needle into the lumbar region of the spine, typically between the third and fourth lumbar vertebrae. Lumbar punctures can help diagnose various conditions, such as meningitis, multiple sclerosis, and subarachnoid hemorrhage. They can also be used to administer medications or relieve pressure in the spinal canal. The procedure is generally safe, though some risks include headache and infection.