Perilymph is a clear fluid found in the inner ear, specifically in the bony labyrinth. It surrounds the cochlea, vestibule, and semicircular canals, playing a crucial role in hearing and balance. This fluid helps transmit sound vibrations and supports the structures of the inner ear. The composition of perilymph is similar to that of extracellular fluid, containing sodium and chloride ions. It is essential for the proper functioning of the hair cells in the inner ear, which convert sound waves into electrical signals sent to the brain for processing.