Ohm's Law states that the current through a conductor between two points is directly proportional to the voltage across the two points. Therefore, a material that obeys Ohm's Law will have a constant resistance at a given temperature. Metals are good conductors and generally obey Ohm's Law, which means their resistance remains constant over a wide range of voltages and currents. On the other hand, electrolytes, such as solutions of salts and acids, do not obey Ohm's Law because they have a non-linear relationship between current and voltage due to their ionic nature. Glass is an insulator and does not conduct electricity, while a diode is a semiconductor that exhibits nonlinear current-voltage characteristics and does not obey Ohm's Law. Therefore, the material that obeys Ohm's Law is "All metals".