A linear displacement sensor converts straight-line motion into an electrical signal for position, distance, or travel measurement. Its principle varies by technology, but the basic process is similar: a movable part follows the target, and a circuit measures how movement changes a physical property such as resistance, inductance, capacitance, magnetic field, or light. Potentiometric sensors use a wiper sliding on a resistive track. Output voltage is a fraction of input voltage, so displacement is proportional to wiper position. They are simple and low-cost, but wear limits life. LVDTs use one primary coil and two secondary coils around a movable iron core. AC excitation drives the primary. As the core moves, magnetic coupling to each secondary changes. Differential voltage amplitude and phase indicate core position. LVDTs offer high accuracy, infinite resolution, and long life. Capacitive sensors measure capacitance changes between plates as the target moves. They detect small displacements but are sensitive to contamination and humidity. Magnetostrictive sensors use a torsional strain pulse in a waveguide; a position magnet creates a wave, and time-of-flight gives distance. They are durable in hydraulic cylinders. Optical and encoder-based sensors count light or dark patterns on a scale. Phase shift or pulse count is converted into linear displacement. They provide high speed and precision. Signal conditioning converts the output into standard signals, such as 0-10 V, 4-20 mA, or digital data.