Quartz: Although not as mechanically complex as other engines, the quartz movement provides the most accurate and reliable time-keeping. This type of movement typically draws power from a battery and centers around a small vibrating chip of quartz crystal. When an electrical current, supplied from a battery, is applied to a quartz crystal, the current is distorted and creates a precise resonating frequency. Watchmakers employ the subsequent frequency to measure time. Some adaptations to the traditional quartz movement include introducing rotors and power cells in an effort to maintain the accuracy of quartz while eliminating the need for a battery. Quartz movements have been used in timepieces since the 1970s and are highly accurate, dependable and affordable.