Feminism is defined as the belief that women and men should have equal rights and opportunities. It arose from the understanding that historically, women have been unable to fully participate in social institutions and have often been treated differently than men. Feminism aims to remedy this situation by eliminating old assumptions about gender roles. There have been three major waves of feminism. The first wave in the late 19th and early 20th centuries focused on women's suffrage and legal rights. The second wave from the 1960s-90s took on issues like reproductive rights and the fight for the Equal Rights Amendment. The third wave since the 1990s challenges concepts like universal womanhood and promotes defining femininity on women's own terms.