The size of a wire in diameter with higher gauges being smaller and lower gauges being larger. For instance, an 18-gauge wire is very thin while a 12-gauge wire is much thicker. In audio, it is generally preferable to use lower gauge wires (12 gauge) whenever possible. The thicker wires allow a musical signal to travel more freely over longer distances and generally allow greater sound quality (similar to poring water down a pipe – much more water can travel faster through a large pipe than a small one). Heavier gauge wires (thicker wires) have less resistance to current flow (impedance) than thinner wires making them preferable for connecting speakers and amplifiers, especially if the lengths of wire are fairly long.