An axon is a thin fiber that conducts electrical impulses away from a neuron, or nerve cell. Axons are an important part of the nervous system.
Your nervous system is what your brain uses to send and receive information about what's going on in and around your body. Neurons, specialized cells that transmit and receive nerve impulses, are made up of dendrites, which bring in electrical signals, and axons, which send them out. Axon gained this meaning in 1899—earlier, it meant "skeletal axis of the body," from the Greek meaning of axon, "axis."