Rotation curves of spiral galaxies

Rotation curves of spiral galaxies are the major tool for determining the d istribution of mass in spiral galaxies. They provide fundamental informatio n for understanding the dynamics, evolution, and formation of spiral galaxi es. We describe various methods to derive rotation curves and review the re sults obtained. We discuss the basic characteristics of observed rotation c urves in relation to various galaxy properties, such as Hubble type, struct ure, activity, and environment.