“Thunderstruck”. Summer stom. A super cell formed off the coast of New Zealand, intensified and swept across Christchurch and North Canterbury, February 23, 2014. Photo location: Christchurch, New Zealand. (Photo and caption by David Hardy/National Geographic Photo Contest)

A woman crosses an open sewer as she makes her way to her house in a Christian slum in Islamabad December 4, 2014. (Photo by Zohra Bensemra/Reuters)

Winner. “I took this picture of a woman in traditional clothing in Cartagena, Colombia”. PAUL GOLDSTEIN, JUDGE: “The blaze of colour from every angle, the boldness of the picture, taken from behind, which gives it so much more allure and frankly a superb get up. Did I mention the colours? Oh, and that looks suspiciously like a Nokia”. (Photo by Stanislav Shmelev/The Guardian)

Andrea Abarca, (C) leads an aerobics class in Los Guidos de Desamparados July 23, 2015. More than 300 women participated in a physical health program organized by Abarca, which aims to combat obesity and sedentary behavior in poor women living in a slum. The National Nutrition Survey shows that the Costa Rican population has 62.4 percent of adult men who are obese, while among women the percentage was 77.3, according to local media. (Photo by Juan Carlos Ulate/Reuters)

Some are in it just for the money, others to help buy a meal. Then there are those who trade for fun or to spend time among friends. Millions of investors – pensioners, security guards, high-school students – dominate China's stock markets, conducting about 80 percent of all trades. Retirees gather in brokerage houses dotted around China also to enjoy some company and savour the air conditioning on hot days. Some start as young as 13, trading from home with an eye on future careers in finance. Winning isn't guaranteed. This year, among the most turbulent in China's financial history, its stock markets more than doubled in the six months to May, only to crash amid concerns that growth in the country, which makes everything from cars to steel, is slowing faster than previously thought. (Photo by Aly Song/Reuters)

“Shortly after he arrived, Van Agtmael witnessed the aftermath of this suicide bombing at a cafe that soldiers frequented in Mosul. Nine people died and 23 were wounded”. (Photo and caption by Van Agtmael/Harrison Jacobs/Magnum Photos)

Shephen Shine, 27, who lost a leg when serving in Iraq in 2007, is tattood with a regimental tattoo reading “Their Sacrifice – Our Freedom” during the Ink For Heroes event on June 18, 2011 in Catterick, England. Ink For Heroes is a charity event to raise money and awareness of the soldiers that get injured during service, with all proceeds going to both “Help The Heroes” and “The British Legion”. Injured soldiers can also get tattooed for free during the event. (Photo by Bethany Clarke/Getty Images)

“At her job, Maria Torero cares for sick human beings. At home, she lavishes love on slowly dying cats – 175 of them at last count. The 45-year-old nurse has turned her two-story, eight-room apartment into a hospice for cats with feline leukemia, scattering it with scores of feeding dishes and at least two dozen boxes litter boxes. Some have suggested she shelter healthy cats instead. “That's not my role”, she told The Associated Press. “I'm a nurse. My duty is to the cats that nobody cares about”. She said that “people don't adopt adult cats, especially if they are terminally ill”. – Franklin Briceno via Associated Press. (Photo by Martin Mejia/AP Photo)