After the Socialist Party of America organized a Women’s Day in New York City on February 28, 1909, German delegates Clara Zetkin, Käte Duncker, Paula Thiede and others proposed at the 1910 International Socialist Woman’s Conference that “a special Women’s Day” be organized annually. After women gained suffrage in Soviet Russia in 1917, March 8 became a national holiday there. The day was then predominantly celebrated by the socialist movement and communist countries until it was adopted by the feminist movement in about 1967. The United Nations began celebrating the day in 1977.
Commemoration of International Women’s Day today ranges from being a public holiday in some countries to being largely ignored elsewhere. In some places, it is a day of protest; in others, it is a day that celebrates womanhood. (Source)