Here's why:

* Myelin: Myelin is a fatty, insulating substance that wraps around the axon of a neuron. It acts as an electrical insulator, preventing the loss of electrical signal as it travels along the axon.

* Nodes of Ranvier: Myelin isn't continuous along the axon. There are gaps in the myelin sheath called Nodes of Ranvier. These gaps are crucial for saltatory conduction.

* Saltatory Conduction: In saltatory conduction, the electrical signal "jumps" from one Node of Ranvier to the next, skipping over the myelinated segments. This jumping action significantly speeds up the transmission of the signal compared to unmyelinated axons.

In contrast, unmyelinated axons do not exhibit saltatory conduction. The electrical signal travels continuously along the axon, which is much slower than in myelinated axons.