International Women's Day 2016: 10 simple ways you can make a difference

The world's 15 most powerful women in 2015

• 1/15 Angela Merkel - German Chancellor

  German Chancellor Angela Merkel has retained her number one ranking for topping this year’s Forbes list for the fifth consecutive year and ten times in total.

• 2/15 Hillary Clinton - Presidential candidate, United States

  Clinton, who could become the world’s most powerful leader in 2016, has been featured on the list every year since it launched in 2014.

• 3/15 Melinda Gates - Cochair, Bill & Melinda Gates Foundation

  Melinda Gates has cemented her dominance in philanthropy and global development to the tune of $3.9 billion in giving in 2014 and more than $33 billion in grant payments since she founded the Bill & Melinda Gates Foundation with her husband in 2000.

• 4/15 Janet Yellen - Chair, Federal Reserve, Washington, United States

  Janet Yellen made history in 2014 when she became the first female head of the Federal Reserve.

• 5/15 Marry Barra - CEO of General Motors

  Mary Barra made history by becoming the first female CEO of General Motors.

• 6/15 Christina Lagarde - Managing director, International Monetary Fund

  Christine Lagarde is entering the last year of her first term heading the International Monetary Fund (IMF), the organisation which serves as economic advisor and backstop for 188 countries. Under Lagarde the IMF has supported efforts to increase female labor force participation as way to reduce poverty and inequality. The UK, Germany, China, France and Korea have endorsed Christine Lagarde for another term as the head of the IMF.

• 7/15 Dilma Rousseff - President, Brazil

  Dilma Rousseff, who has been elected in 2010, is Brazil's first female president.

• 8/15 Sheryl Sandberg - COO of Facebook

  Sheryl Sandberg, Facebook COO and author of bestseller “Lean In,” joined the company in 2008 and became the first woman on its board four years later. Sandberg helped the social network go public and expand digital revenue.

• 9/15 Susan Wojcicki - CEO of Youtube

  Susan Wojcicki is CEO of YouTube, the world’s most popular digital video platform used by over a billion people across the globe. She oversees YouTube's content and business operations, engineering, and product development.

• 10/15 Michelle Obama - First lady, United States

  Michelle Obama, the 44th first lady of the United States has focused her attention on issues such as the support of military families, helping working women balance career and family and encouraging national service.

• 11/15 Park Geun-hye - President, South Korea

  Park Geun-hye is the first female leader of a country that has the highest level of gender inequality in the developed world. In her inauguration speech, she promised to prioritise both national security and economic revitalisation.

• 12/15 Oprah Winfrey - Actress, Director/Producer, Entrepreneur, Personality, Philanthropist

  Oprah Winfrey, a former queen of daytime TV has proven she can thrive without a talkshow. Her 'The Life You Want' tour sold out stadiums from Newark to Seattle in 2014.

• 13/15 Ginni Rometty - CEO of IBM

  Ginni Rometty joined IBM in 1981 and later became the first woman to lead the company.

• 14/15 Meg Whitman - CEO of Hewlett-Packard

  Meg Whitman is the only woman to have headed two large U.S. public companies: eBay and Hewlett-Packard.Until Marissa Mayer's arrival at Yahoo, she was the only female head of a leading Internet-based company.

• 15/15 Indra Nooyi - CEO of PepsiCo

  Indra Nooyi is Chairman and Chief Executive Officer of PepsiCo. Mrs. Nooyi leads one of the world’s largest convenient food and beverage companies, with 2008 annual revenues of more than $43 billion.