Output Impedance
The low output impedance of an op-amp is an important characteristic which makes VOUT independent of the load current drawn from VDD. However, the precise output impedance of an op-amp is usually not specified.
Feedback decreases op-amp output impedance. ZIN’ = ZIN / (1 + βA) which makes the op-amp more close to ideal. Recall that the ideal output impedance is zero.
