Equal Pay Day represents the day in the year women have to work until to make as much as men did in the previous year.
On average, women make 79 cents for every dollar men earn. Based on that, women have to work until April 12, 2016 to make as much as men did in 2015.
Here are a few things you should know about the day.
1. Equal Pay Day was started in 1996 by the National Committee on Pay Equity.
It is supposed to bring attention to the ongoing gender pay gap.
2. The gender pay gap differs based on race, and women of color are disproportionately affected.
African American women make 63 percent of what white men do while Latina women make 54 percent.
Equal Pay Day would be on August 23 for African American women, September 13 for Native American women and November 1 for Latina women, according to reports.
3. No, women do not earn less because of their job choices.
Women make less than men do even when they are in the same profession.
4. The gender pay gap exists at all levels of professional success and across industries.
Women in Hollywood are beginning to more frequently call out the pay disparities they face. When Sony was hacked, for instance, Jennifer Lawrence found out she was paid less than her male co-stars.
The United States women's national soccer team, who won the World Cup last year, filed a wage-discrimination complaint against US Soccer last month.
5. President Barack Obama is designating a national monument for women's equality.
The White House announced Obama is recognizing the National Women's Party headquarters as the Belmont-Paul Women's Equality National Monument on Equal Pay Day.
6. The Democratic presidential candidates have spoken out for Equal Pay Day.
Hillary Clinton shared a video of her talking about equal pay.
Bernie Sanders also tweeted about Equal Pay Day.
7. The Republican candidates have stayed quiet.
In the fall, John Kasich said differences in pay are due to "experience" and "skills," along with other factors. Donald Trump said he supports equal pay, but he has also said it's related to skill. Ted Cruz voted against the Paycheck Fairness Act three times.