How did this holiday get started? The first National Women’s Day was observed in the United States in 1909. Two years later, International Women's Day celebrations started popping up in a number of other countries as more than a million people began rallying for women's rights around the world.

According to the United Nations, the overall theme for this year's International Women's Day is "Empower Rural Women — End Hunger and Poverty."The European Parliament is celebrating the day with the slogan "Equal Pay for Work of Equal Value," while the International Women's Day site is using "Connecting Girls, Inspiring Futures."

Thousands of events will be held around the world — both today and all month long — to honor women's causes and achievements and raise awareness about issues affecting women's rights. A number of notable celebrities and politicians, including actresses Angelina Jolie and Meryl Streep and U.S. Secretary of State Hillary Rodham Clinton, will meet in New York today for the third annual Women in the World Summit. Head over to the International Women's Day site for a listing of other U.S. events in honor of the day.

Around the Web, you can learn more about the role of important women in history, check out slideshows of extraordinary women here or get inspired by this post on 12 innovations that are helping women nourish the planet.

Happy International Women's Day! How do you plan to celebrate?

Celebrating International Women's Day
Take time today to celebrate, honor, learn about, fight for, and raise a glass to all of the women of the world.