The myelin layer is a white fatty and protein covering that insulates and protects a nerve fiber. The concept of myelin can be thought of as similar to the insulating coatings that typically surround electrical wiring. Just like insulators are needed to protect electrical wires, myelin is needed to protect our nerve fibers which incidentally, conduct electrical current also.
Myelin is made up of roughly about 80% fat, and about 20% protein. In addition to protecting our nerves, having a myelin covering or sheath allows nerve signals to be transported much quicker and more effectively. When the myelin sheath is damaged, impulses do not get transmitted through the nerve as quickly as it should. In addition, much like a damaged insulator covering can result in frayed wiring, a compromised myelin sheath can result in the underlying nerves becoming damaged as well. Neuropathy symptoms are often the result of this damage.