Op Amp Specifications
Input Offset Voltage

The Input Offset Voltage is the voltage needed to balance the inputs of an op amp so that no imbalances exist between them that would produce an output voltage.

In theory, the output voltage of an op amp should be zero when both inputs are zero. In reality, however, a slight circuit imbalance with in the internal circuitry can result in an output voltage. The input offset voltage is the amount of voltage that must be applied to one of the inputs to zero the output. This, in turn, will balance the inputs so that they're equal and no output voltage will be produced.