Microplasmas are nonequilibrium plasmas formed in submillimeter discharge structures. They are typically operated at elevated pressures (tens of Torr to several atmospheres) and at modest power levels on the order of less than 1 W to several Watts. In many aspects, they resemble low-pressure glow and capacitively coupled plasmas scaled to much higher pressures. This entry compares microplasmas to other types of discharges and discusses some of the physical processes that increase in importance at higher gas pressures. The range of different microplasma source designs and some of their potential applications are also reviewed.