Definition: The maximum value of the reverse voltage that a PN junction or diode can withstand without damaging itself is known as its Peak Inverse Voltage. This rating of Peak Inverse Voltage (PIV) is given and described in the datasheet provided by the manufacturer.
However, if the voltage coming across the junction at reverse biased condition increases beyond this specified value, the junction will get damaged.
As usually, a PN junction or diode is used as a rectifier as shown in the figure above, i.e., it is used to convert AC to DC. Therefore, care should be taken that during the negative half cycle, the peak value of AC voltage should not be more than the rated value of the Peak Inverse Voltage of the diode.