If I write some code and you write some code and we have the same job title, we'll get paid the same amount, right? Well, no, actually.

That's because of something called the Gender Pay Gap. "[It's] a number that represents the difference between what a man makes for an hour of work, on average, and what a woman makes," said Sheelah Kolhatkar features editor for Bloomberg Businessweek.

You see, for every $1 that a man makes on average, a woman only makes $0.78. "Once you graduate from college, you take a guy and a young woman -- they have the same major and the woman might have even gotten better grades than the guy, which is often the case -- so the woman could maybe be making $0.90 for the $1 that the guy is making."

And that is actually the lowest the gap between what they earn is ever going to be because every year they're in the workforce the gap gets wider and wider. By one year later it's $0.82 and by the time she's 35 it's up to $0.78, and it just continues to widen over the course of her work life.

Then what happens when the couple wants to start a family? Who stays home and sacrifices their career for the kids?

"Women sometimes get pushed into doing that because they're earning less money in the house," Kolhatkar said. "And once you do that. Once you quit or take time out or drop out it's really hard to ever recover."

According to a recent report, the gap is real in every state and nearly every occupation, it is worse for women of color and while education helps, it's not a cure-all.