International Women’s Day is on March 8, and with the #metoo movement forcing unprecedented changes for women around the world, there seems no better time to keep pushing forward for change.

This year, the theme of the annual campaign is #eachforequal, championing actions of the individual to help create a gender-equal world. Gender equality in America has come a long way, and still has a long way to go. But do you know where the movement began in America?

This year marks 100 years since the ratification of the 19th Amendment in the US, a landmark moment in the progress of women's rights.

Below is a crash course in how and when the amendment was passed, its significance in the fight for equality in America and the importance of the actions of the individuals who made it happen.

10 quotes from women that defined the decade Show all 10 1 /10 10 quotes from women that defined the decade 10 quotes from women that defined the decade Malala Yousafzai "One child, one teacher, one pen and one book can change the world." United Nations Youth Assembly, New York, 2013 Getty 10 quotes from women that defined the decade Michelle Obama “Whether it was during my time as a lawyer, as an administrator at a university, a nonprofit manager, even now as First Lady, I’ve never once asked someone I was interviewing to explain a test score or a grade in a class -- never. I’ve never once made a hire just because someone went to an Ivy League school instead of a state school -- never. What I have looked for is what kind of person you are. Are you a hard worker? Are you reliable? Are you open to other viewpoints? Have you stepped outside of your own self-interest to serve others? Have you found a way to serve our country, whether in uniform or in your community?” Commencement address at Eastern Kentucky University, Kentucky, 2013 Getty 10 quotes from women that defined the decade Emma Watson "I have realized that fighting for women’s rights has too often become synonymous with man-hating. If there is one thing I know for certain, it is that this has to stop." United Nations, New York, 2014 Getty Images 10 quotes from women that defined the decade Patricia Arquette “To every woman who gave birth to every taxpayer and citizen of this nation, we have fought for everybody else’s equal rights. It’s our time to have wage equality once and for all." Academy Awards, California, 2015 Getty Images 10 quotes from women that defined the decade Hillary Clinton "All the evidence tells us that despite the enormous obstacles that remain, there has never been a better time in history to be born female. But the data leads to a second conclusion: That despite all this progress, we're just not there yet." Women in The World Summit, New York, 2015 Getty Images 10 quotes from women that defined the decade Gloria Steinem “We are here and around the world for a deep democracy that says we will not be quiet, we will not be controlled, we will work for a world in which all countries are connected. God may be in the details, but the goddess is in connections. We are at one with each other, we are looking at each other, not up." Women's March in Washington DC, 2017 Getty Images 10 quotes from women that defined the decade Oprah Winfrey “So I want all the girls watching here and now to know that a new day is on the horizon! And when that new day finally dawns, it will be because of a lot of magnificent women, many of whom are right here in this room tonight, and some pretty phenomenal men, fighting hard to make sure that they become the leaders who take us to the time when nobody ever has to say, ‘Me too’ again. Thank you.” Golden Globe Awards, California, 2018 NBCUniversal via Getty Images 10 quotes from women that defined the decade Emma Gonzalez "So we are speaking up for those who don’t have anyone listening to them, for those who can’t talk about it just yet, and for those who will never speak again. We are grieving, we are furious, and we are using our words fiercely and desperately because that’s the only thing standing between us and this happening again.” March for Our Lives rally, Washington DC, 2018 Getty Images 10 quotes from women that defined the decade Tarana Burke “So much of what we hear about the Me Too Movement is about individual bad actors or depraved, isolated behavior, and it fails to recognize that anybody in a position of power comes with privilege, and it renders those without that power more vulnerable. Teachers and students, coaches and athletes, law enforcement and citizen, parent and child: these are all relationships that can have an incredible imbalance of power. But we reshape that imbalance by speaking out against it in unison and by creating spaces to speak truth to power. We have to reeducate ourselves and our children to understand that power and privilege doesn't always have to destroy and take -- it can be used to serve and build. And we have to re-educate ourselves to understand that, unequivocally, every human being has the right to walk through this life with their full humanity intact.” Ted Women, California, 2018 Getty Images for Comedy Central 10 quotes from women that defined the decade Greta Thunberg "The eyes of all future generations are upon you. And if you choose to fail us, I say - we will never forgive you." UN Climate Summit, New York, 2019 Getty Images

What is the 19th amendment?

In short, the 19th amendment lifted discrimination on the basis of sex, paving the way for women to vote. It signposted the granting of women’s suffrage after a long and hard-won protest by women across America.

The victory for women came after a gruelling and militant century-long campaign by the women’s rights movement, causing the injury of hundreds of women and the arrests of others.

Reformers Elizabeth Cady Stanton and Lucretia Mott are often regarded as figureheads of the movement, after launching the women’s rights movement in 1948. Women began pushing for the realisation of a federal amendment that would legally grant women the right to vote.

After a failed proposal’s to the senate in 1887, 1914 1918 and attempts to lobby for votes on a state by state basis, the amendment finally came back up for measure one last time in 1919.

When was it passed and ratified?

The amendment was passed at the House on 21 May and the US Senate, by two vote’s majority, on the 4 June 1919. However, this didn’t mean it came into force straight away as it had to endure the lengthy process of ratification.

To be successful women’s votes had to be ratified by three-fourths of the states in the US. Between the passing of the bill in June, and March the following year, 35 states had approved the amendment. However, the bill was still one state short of being approved before its ratification.

It came down to one man persuaded by his mother

Southern states were staunchly against the bill and the success or failure of women’s suffrage was laid at the feet of the state of Tennessee. The votes on the bill were tied at 48-48 and the fate of the state’s position, and more importantly, the amendment came down to one man.

23-year-old republican Harry Burn cast the deciding vote and was persuaded by his mother to approve it despite his own personal opposition to the bill. With the deciding vote, the ratification of the bill was narrowly passed and votes for women officially ratified on 18 August 1920.

What does the constitution say about who can vote?

Women finally got the vote in the US when the Amendment was certified on 26 August 1920, and in the November election of that year, women voted in elections for the first time. The Amendment prevents the US government from denying citizens of America suffrage based on gender.

The amendment itself reads: “The right of citizens of the United States to vote shall not be denied or abridged by the United States or by any State on account of sex. Congress shall have the power to enforce this article by appropriate legislation.”