I was confused about op-amps and asked this question: In an op-amp, why does Vn approach Vp until the difference is delta V / A? Why doesn't Vn just equal Vp? and received really helpful answers.
I now know why in a real-world op-amp, Vn has to differ from Vp; Vn can't just equal Vp or else the output voltage will equal 0. However, how does a real-world op-amp ensure that Vp and Vn differ by a small amount? How does it make sure that Vn doesn't increase to equal Vp? How does it ensure that the difference between Vp and Vn is Vp - (Vp - Vn) / A instead of 0?