Throughout the course of the long war in Afghanistan, Coalition troops have relied on thousands of military working dogs to help keep them safe, and make their jobs easier. The dogs are trained to detect explosives, to find illegal drugs, to search for missing comrades, or target enemy combatants. Not only are they active on the front lines, but behind the lines they serve as therapy dogs, service dogs, and loyal companions. They also share the same risks as the ground troops, suffering injuries and sometimes death on the battlefields. Gathered here are images of these dogs and their handlers in Afghanistan and back home, from over the past several years, part of the ongoing series here on Afghanistan.

A Russian digital artist Svetlana Petrova has taken her love of cats to the next level – by adding her furry friend to some of the world's greatest artwork. Svetlana has placed photos of her tabby, called Zarathustra, posing alongside the most well-known pieces in history for her UK exhibition. (Photo by Svetlana Petrova/Zarathustra the Cat)

Sports have the ability to transform groups of strangers into a united community. In the celebratory spirit surrounding the 2014 FIFA World Cup, Sony and the World Photography Organisation present UNITED – a contest honouring the passion of football fans around the world. Seven inspirational photographers have been selected by Sony and WPO to capture the atmosphere and celebration of the World Cup across the globe. Photo: France – French fans cheering for their team. (Photo by Anthony Lepinay)

Only the most intrepid urban explorers cross the tattered ruins of the old Iron Curtain to endure the excessive bureaucracy, military paranoia and freezing winds of the East to hunt for the ghosts of an empire. Rebecca Litchfield is one who couldn’t resist the haunting allure of the ruins of the Soviet Union.

“I started photography in June 2009. At the time, I was searching for a way to express both the rigorous scientist and the creative artist in me. There are few hobbies that let these two approaches work together, so I really was enthusiastic about it: I am now spending all my free time studying various techniques, contemplating others' fantastic work, and of course, making pictures”. – Christophe Kiciak. Photo: “The Hero”. (Photo by Christophe Kiciak)

Tanzania, 1964. A touching moment between primatologist and National Geographic grantee Jane Goodall and young chimpanzee Flint at Tanzania's Gombe Stream Reserve. (Photo by Hugo van Lawick via National Geographic)

“Not for the faint of heart”. Casa Milà, better known as La Pedrera, is a building designed by the Catalan architect Antoni Gaudí and built during the years 1905–1910, being considered officially completed in 1912. It is located at 92, Passeig de Gràcia in the Eixample district of Barcelona, Catalonia, Spain. (Photo by Stefano Scarselli)