Electric thrusters are propulsion devices that provide a thrust that operates on the spacecraft using the idea of momentum conservation. Electric thrusters have become a popular option for micro-satellite propulsion because of their propellant efficiency, reliability and versatility. Propellant is accelerated using various electrical and/or magnetic physical principles. Because the propellant is ejected at velocities significantly higher than a conventional chemical thruster, electric propulsion is much more fuel efficient, ultimately requiring smaller amounts of propellant. Several electric thruster technologies exist, covering a large range of missions and requirements. Over the years, these technologies have faced operational challenges and enabled several types of maneuvers, such as electric transfer from GTO to GEO, station keeping, inter-orbital transfer, interplanetary cruise, deorbiting and collision avoidance maneuvers.