What is meant by the phrase saltatory conduction?

Saltatory conduction refers to the passage of an action potential along a myelinated neurone. Myelin is a lipid that forms a fatty sheath around the neurone axon and it is an electrical insulator. This means that an action potential cannot pass where there is myelin. However there are gaps in the myelin sheath called Nodes of Ranvier and action potentials can occur here because there is no myelin to stop it. Therefore the action potential 'jumps' from node to node. This process is called saltatory conduction and allows much faster passage of the action potential than in a non-myelinated neurone.