Short answers, pulled from the story.
The Socialist Party of America organized the first Woman's Day event on the 28th of February 1909 in New York City. Activist Theresa Malkiel suggested holding this gathering to highlight women's labor struggles and garment workers who had protested for better conditions earlier that month.
Clara Zetkin, a communist activist and politician from Germany, proposed expanding the idea at an International Socialist Women's Conference in Copenhagen during August 1910. Delegates representing seventeen countries agreed to support equal rights including women's suffrage without specifying a date.
Vladimir Lenin declared the 8th of March as International Women's Day in 1922 to honor women's role in the Russian Revolution. Textile workers in Petrograd began a demonstration on the 8th of March 1917 demanding bread and peace which triggered the February Revolution leading to Tsar Nicholas II abdicating seven days later.
The United Nations began celebrating International Women's Day in 1975 which had been proclaimed the International Women's Year. In 1977 the UN General Assembly invited member states to proclaim any day as United Nations Day for Women's Rights and International Peace with most countries recognizing the 8th of March as the traditional date for observance.
By the twenty-first century critics argued International Women's Day became heavily diluted and commercialized especially in Western nations where major corporations began sponsoring events using vague notions of equality rather than radical social reforms. The website internationalwomensday.com established in 2001 managed by British marketing firm Aurora Ventures promoted hashtags unconnected with UN themes while business breakfasts drew comparisons to Mother's Day greetings.