Perilymph and endolymph are two distinct fluids found within the inner ear, playing crucial roles in the process of hearing and balance. Perilymph, similar in composition to cerebrospinal fluid, fills the space between the bony labyrinth and the membranous labyrinth, while endolymph, rich in potassium, fills the membranous labyrinth itself, creating an electrochemical gradient essential for sensory transduction.