Explain the concepts of wage gap and wage penalty in the American context

What will be an ideal response?

In the United States, the wage gap between men and women—the difference between what a man and a woman earn for doing the same exact job—is almost entirely a function of whether a woman has children: childless women earn just about as much as their male counterparts, while women who have children earn less than
75 percent of what an otherwise?similar man does. Given this, in the United
States—but to a lesser extent elsewhere, partly due to variation in government support for working parents—a "nuclear" family in which both parents work suffers a wage penalty—meaning that the men, women, and children in such families pay a financial price over the long run.