A photographer tested the concentration of several pairs of dogs as he captured their reactions to treat time in a series of shots. Christian Vieler, 47, of Waltrop, Germany, has been a professional dog photographer since 2016. He came up with the idea of snapping two dogs catching treats simultaneously. Here: Basset Hounds. (Photo by Vieler Photography/Caters News Agency)

An injured protestor is led away during clashes with police near Tahrir Square on November 23, 2011 in Cairo, Egypt. Thousands of Egyptians are continuing to occupy Tahrir Square after four days of clashes with security forces despite a promise from military leaders to bring forward Presidential elections. (Photo by Peter Macdiarmid/Getty Images)

A bulldog dressed as Marilyn Monroe poses for a photograph during the annual Tompkins Square Halloween Dog Parade in the Manhattan borough of New York City, October 24, 2015. (Photo by Stephanie Keith/Reuters)

In Mumbai, the windows of new high-rise apartment blocks, old low-rise residential buildings and shantytown shacks portray the disparity in living conditions and incomes in the Indian city. Rents for a place to live range from more than $2,000 to less than $5 a month. Here: Windows and doors of an old residential building are pictured in central Mumbai October 10, 2014. The cost for buying a residential apartment in Mumbai close to the city centre ranges from 12,000 Indian rupees ($ 200) per square feet to 112,552 Indian rupees ($ 1800) per square feet. (Photo by Danish Siddiqui/Reuters)

The November 2018 Square Print Sale, presented by Magnum Photos and Aperture, brings together over 100 images to explore perspectives on transition and transformation in photography. Here: New York City, 1965, by Joel Meyerowitz. “A girl on a Vespa on her way to who knows where, when the light stopped her at the 72nd street crossing near the Dakota, where John Lennon would one day cross paths with his fate. She takes this moment to finesse a fingernail before she resumes her downtown journey, while I, stopping at the same crossing, but on foot, leap into the street to capture this vision of a dream girl before time takes her on her way”. (Photo by Joel Meyerowitz/Courtesy Aperture)

These stunning photos act as postcards for one photographer, who has traveled all over the globe, braving freezing temperatures to create the ultimate time lapse video. Photographer Dustin Farrell, 36, spent four years perfecting his technique and traveling all over the world in his quest to capture the most beautiful time lapses of nature. (Photo by Dustin Farrell/Caters News)

A reveller takes part with her dogs in the annual halloween dog parade at Manhattan’s Tompkins Square Park in New York, U.S. October 22, 2016. (Photo by Eduardo Munoz/Reuters)

Actors perform “The Passion of Jesus” to crowds in Trafalgar Square on April 22, 2011 in London, England. The actors come from the Wintershall Estate in Surrey where they also perform a Nativity play in and around the farm buildings at Christmas. (Photo by Peter Macdiarmid/Getty Images)