Nerve fibers are long, slender projections of nerve cells, or neurons, that transmit electrical signals throughout the body. They are essential for communication between the brain, spinal cord, and other parts of the body, allowing for the coordination of movements and responses to stimuli. There are two main types of nerve fibers: myelinated and unmyelinated. Myelinated fibers are covered with a fatty substance called myelin, which speeds up signal transmission, while unmyelinated fibers lack this covering and transmit signals more slowly. Together, these fibers play a crucial role in the functioning of the nervous system.