Gender roles are the typical roles attributed to a specific gender of humans.
Traditional Male roles
Typically men throughout history have been given the responsibility of providing for his family or society, whether in terms of money, food, housing, protection, or any number of other things.
Traditional Female roles
Typically women throughout history have been given the responsibility of motherhood. Giving birth, raising children, and in some time periods and societies, home-schooling them.
Changes through time in gender roles
In western culture, there has been a remarkable change in the prevalence and demand on gender roles; or mainly, divergence from them. In America during the 19th century, it was unheard of for a woman to have a physical job, if they had a job at all. But during the World Wars and other major wars, when great numbers of men joined the military and had to go away and fight, the women were the only ones available to do the jobs left by the men. And thus, America saw a greatly emerging feminine workforce, popularized by Rosy the Riveter during WWII. Since the beginning of the 20th century (especially in the 1920s) women have been taking more leeway in how they go about their daily lives and what kind of lives they lead. As such, expectations of them have changed too, as seen in one instance by the hard-earned success of gaining women's suffrage.