We have discussed all of the properties of the ideal op amp except for one, which in fact is the most important. The has to do with the value of A. The ideal op amp should have a gain A whose value is very large and ideally infinite. One may justifiably ask: If the gain A is infinite, how are we going to use the op amp? The answer is very simple: In almost all applications the op amp will not be used alone in a so-called open-loop config-uration. Rather, we will use other components to apply feedback to close the loop around the op amp, as will be illustrated in detail in Section 2.3.