The role of myelin in the nervous system is to insulate nerve fibers, enhancing the speed of electrical signal conduction. Myelin forms a protective sheath around axons, which allows for the efficient transmission of action potentials. This insulation is crucial for proper nervous system function, as it increases the conduction velocity of impulses, enabling quick communication between different parts of the body. Damage to myelin can lead to neurological disorders, such as multiple sclerosis, where signal transmission is impaired.