Which digital code allows only one bit to change between sequential code values?

Gray code is a specialized binary numeral system structured so that only one single bit changes state between any two consecutive values. For example, counting from 0 to 3 in a 2-bit Gray code sequence goes 00, 01, 11, 10. In contrast, standard binary counting (00, 01, 10, 11) often requires multiple bits to flip at once, such as transitioning from 01 (one) to 10 (two). In physical systems, if these bits do not change state at the exact same microsecond, the system might briefly read an unintended intermediate value, causing a glitch. Because only one bit transitions at a time, Gray code eliminates these transitional errors. It is heavily utilized in mechanical rotary encoders, absolute position sensors, and certain digital modulation schemes to minimize data corruption.