How does a Wheatstone bridge work and what are its applications?

A Wheatstone bridge consists of four resistors in a diamond configuration with a voltage source and a galvanometer. When balanced (no current through galvanometer), the ratio R1/R2 = R3/R4. It is used for precision resistance measurement by comparing unknown resistance to known standards, achieving accuracy of 0.1% or better. Applications include strain gauge measurements, temperature sensing with RTDs, and sensor interface circuits.