linear and non linear devices

linear devices are those devices which have linearity between current and voltages. (ohm's law).
it mean's that the graph between current and voltage must be linear
 linear mean's straight line.
example of linear devices are resistor, inductor , capacitor etc.

while non linear devices are whose device which are vice versa to linear devices mean's that do not have linearity between current and voltages the graph of there output is not staight line.
example is diode.
because it doesn't behave like resistor its forward bais and reverse bais properties doesn't form's a liearity to its input that's why it's a non linear device.