Encoders can be either absolute or incremental. Absolute encoders have a unique code for each shaft position. Or in other words, every position of an absolute encoder is distinctive. The absolute encoder interprets a system of coded tracks to create position information where no two positions are identical. Another feature is that absolute encoders do not lose position whenever power is switched off. Since each position is distinctive, the verification of true position is available as soon as power is switched on. So it's not necessary to initialize the system by going back to a home base for a reference.