"The gender pay gap or gender wage gap is the average difference between the remuneration for men and women who are working. Women are generally found to be paid less than men. There are two distinct numbers regarding the pay gap: non-adjusted versus adjusted pay gap. The latter typically takes into account differences in hours worked, occupations chosen, education and job experience. In the United States, for example, the non-adjusted average woman's annual salary is 79% of the average man's salary, compared to 95% for the adjusted average salary.
The reasons link to legal, social and economic factors, and extend beyond 'equal pay for equal work'.
The gender pay gap can be a problem from a public policy perspective because it reduces economic output and means that women are more likely to be dependent upon welfare payments, especially in old age."
From Wikipedia