The selfie is the most popular photography trend of the internet today. It's gotten so popular, in fact, that even our beloved feline friends have started to catch on. I dare you to keep the smile off your face for this one!

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.

Mug shot of De Gracy (sic) and Edward Dalton. Details unknown. Central Police Station, Sydney, around 1920. (Photo by NSW Police Forensic Photography Archive, Justice & Police Museum, Histiric Houses Trust of NSW)

Naturally, it is important that a baby learn the right habits. This woman demonstrates that smoking is wrong for babies. From a series of images parodying women's lifestyle and beauty magazines. (Photo by Jacobsen/Getty Images). 1955

English supermodel Jourdan Dunn wearing Vivienne Westwood for FLANNELS departs The Standard London for this year’s Fashion Awards on December 02, 2019 in London, England. (Photo by David M. Benett/Dave Benett/Getty Images for Flannels)

The Duchess of Cambridge joins Family Action at a Christmas Tree Farm to mark her new patronage, in Great Missenden, Buckinghamshire, UK, on the 4th December 2019. (Photo by James Whatling/The Mega Agency)

Singer Halsey attends a basketball game between The Los Angeles Lakers Vs the Cleveland Cavaliers at the Staples Center in Los Angeles, Ca. on January 13, 2020. (Photo by London Entertainment/Splash News and Pictures)

American actress Sarah Hyland at arrivals for 26th Annual Screen Actors Guild Awards – Part 2, Shrine Auditorium, Los Angeles, CA January 19, 2020. (Photo by Monica Almeida/Reuters)