International Women’s Day first emerged from the activities of labour movements
International Women’s Day first emerged from the activities of labour movements at the turn of the twentieth century in North America and across Europe. Since those early years, International Women’s Day has assumed a new global dimension for women in developed and developing countries alike. The growing international women’s movement, which has been strengthened by four global United Nations women’s conferences, has helped make the commemoration a rallying point to build support for women’s rights and participation in the political and economic arenas.
Increasingly, International Women’s Day is a time to reflect on progress made, to call for change and to celebrate acts of courage and determination by ordinary women who have played an extraordinary role in the history of their countries and communities.
The 2016 theme for International Women’s Day is “Planet 50-50 by 2030: Step It Up for Gender Equality”. The United Nations observance on 8 March will reflect on how to accelerate the 2030 Agenda, building momentum for the effective implementation of the new Sustainable Development Goals. It will equally focus on new commitments under UN Women’s Step It Up initiative, and other existing commitments on gender equality, women’s empowerment and women’s human rights
“We have shattered so many glass ceilings we created a carpet of shards. Now we are sweeping away the assumptions and bias of the past so women can advance across new frontiers.”
UN Secretary-General Ban Ki-moon in his message for International Women’s Day 2016.
http://www2.unwomen.org/en/news/in-focus/international-womens-day
(and should any half-witted responses such as "why isn't there an International Man's Day?" arise, avoid rolling your eyes-- let the poor, oppressed soul know it's celebrated annually on November 19)