The First Wave:
What historians refer to as "first-wave feminism" arguably began in the late 18th century with the publication of Mary Wollstonecraft's Vindication of the Rights of Woman (1792), and ended with the ratification of the Twentieth Amendment of the U.S. Constitution, which protected a woman's right to vote. First-wave feminism was concerned primarily with establishing, as a point of policy, that women are human beings and should not be treated like property.
The Second Wave:
The second wave of feminism emerged in the wake of World War II, during which many women entered the workforce, and would have arguably ended with the ratification of the Equal Rights Amendment (ERA), had it been ratified. The central focus of the second wave was on total gender equality--women as a group having the same social, political, legal, and economic rights that men have.
Rebecca Walker and the Origins of Third-Wave Feminism:
Rebecca Walker, a 23-year-old, bisexual African-American woman born in Jackson, Mississippi, coined the term "third-wave feminism" in a 1992 essay. Walker is in many ways a living symbol of the way that second-wave feminism has historically failed to incorporate the voices of many young women, non-heterosexual women, and women of color.
Women of Color:
Both first-wave and second-wave feminism represented movements that existed alongside, and at times in tension with, civil rights movements for people of color--a slight majority of whom happen to be women. But the struggle always seemed to be for the rights of white women, as represented by the women's liberation movement, and black men, as represented by the civil rights movement. Both movements, at times, could have been legitimately accused of relegating women of color to asterisk status.
Lesbians, Bisexual Women, and Transgender Women:
For many second-wave feminists, non-heterosexual women were seen as an embarrassment to the movement. The great feminist activist Betty Friedan, for example, coined the term "lavender menace" in 1969 to refer to what she considered the harmful perception that feminists are lesbians. She later apologized for the remark, but it accurately reflected the insecurities of a movement that was still very heteronormative in many ways.
First- and second-wave feminism also tended to emphasize the rights and opportunities of middle-class women over poor and working-class women. The debate over abortion rights, for example, centers on laws that affect a woman's right to choose an abortion--but economic circumstances, which generally play a more significant role in such decisions today, are not necessarily taken into account. If a woman has the legal right to terminate her pregnancy, but "chooses" to exercise that right because she can't afford to carry a pregnancy to term, is this really a scenario that protects reproductive rights?
Women in the Developing World:
First- and second-wave feminism, as movements, were largely confined to industrialized nations. But third-wave feminism takes a global perspective--not by merely attempting to colonize developing nations with Western practices, but by empowering women to actualize change, to gain power and equality, within their own cultures and their own communities and with their own voices.
A Generational Movement:
Some second-wave feminist activists have questioned the need for a third wave. Others, both inside and outside of the movement, disagree with respect to what the third wave represents. Even the general definition I've provided above may not accurately describe the objectives of all third-wave feminists.
But it's important to realize that third-wave feminism is a generational term--it refers to how the feminist struggle manifests itself in the world today. Just as second-wave feminism represented the diverse and sometimes competing interests of feminists who struggled together under the banner of women's liberation, third-wave feminism represents a generation that has begun with the achievements of the second wave. We can only hope that the third wave will be so successful as to necessitate a fourth wave--and we can only imagine what that fourth wave might look like.