Used to use it for contact-switches. You turn a knob, say four brushes slide across copper contacts to encode knob position. If you coded position in binary you

Used to use it for contact-switches. You turn a knob, say four brushes slide across copper contacts to encode knob position. If you coded position in binary you'd be sparking several bit-changes which for some instants would jump all over the number range, e.g. from three (011) to four (100) could instantaneously go to seven (111) or two (010) etc. Grey code would at most oscillate between the two values e.g. from 010 (three in Grey Code) to 110 (four in Grey Code).