Io is the dominant source of plasma for the Io plasma torus (IPT), a donut shaped region of plasma centered roughly at Io?s orbital radius of 5.9 Rj. O+, O2+, S+, S2+, SO2+, and electrons with an energy of 10-40 eV are the primary iogenic components of the IPT. Torus plasma properties such as number density and composition have been observed to be variable over time, with the electron number density showing an order of magnitude increase since Pioneer measurements were taken. Thermal measurements indicate the structure of the torus may be divided into a hot narrow ribbon like structure just inside Io?s orbit, a cool inner torus inside the hot ribbon extending from 4.5 – 5.3 Rj, and a hot outer torus extending to 7.5 Rj. Ions and electrons are injected from Io into the IPT either directly, or via extensive neutral gas clouds which coexist with the IPT. Neutral Cloud Theory (NCT) is used to model the plasma properties of the torus, but its predictions fail to agree with certain observations. Corotation of the torus plasma is enforced by JxB forces resulting from a corotating electric field Eco directed radially outward from Jupiter. The IPT radiates much of the energy generated due to corotation in the extreme ultraviolet, ultraviolet, and optical wavelengths. The relative motion of Io through the plasma of the corotating IPT causes Io to act as a unipolar generator, producing a current system which links Io to the ionosphere of Jupiter. This current system is known as the Io flux tube (IFT) and may be modeled as Alfvén waves in the bundle of magnetic field lines which instantaneously thread Io. The energy flux in the IFT is the source for Jupiter?s decametric radio emissions, as well as the auroral emissions at the ends of the IFT.