Compare incremental and absolute encoders for position measurement.

Incremental encoders output pulses as shaft rotates, with channels A and B in quadrature (90-degree phase shift) for direction detection, and index pulse Z for home reference. Position is counted from startup/homing - power loss loses position. Absolute encoders output unique code for each position (binary, Gray code), maintaining position through power loss. Single-turn gives position within one revolution; multi-turn tracks multiple revolutions. Trade-offs: incremental are simpler and cheaper; absolute provide immediate position on power-up and no counting errors from missed pulses.