A nerve fiber, also called axon, is an extension of a nerve cell that transmits electrical impulses and ensures information transfer in the brain.
Some axons are longer than one meter. They are wrapped with an insulating layer called myelin. Myelin conducts electrical signals extra quickly.
An axon conducts signals from the nerve cells, a dendrite conducts signals to them. Axons are long and thin, dendrites are thick and highly branched.