For example, the “current-voltage characteristics” of a bipolar transistor can be shown with various amounts of base drive or the I-V characteristic curves of a diode operating in both its forward and reverse regions.
But the static current–voltage characteristics of a component or device need not be a straight line. Take for example the characteristics of a fixed value resistor, we would expect them to be reasonably straight and constant within certain ranges of current, voltage and power as it is a linear or ohmic device.