“We've reached 40km.” – Participants run at the 40km mark of the 2025 Chosun Ilbo Chuncheon Marathon, held in Chuncheon, Gangwon Province, South Korea on the afternoon of the October 26, 2025. (Photo by Park Seong-won)

An artist draws a tattoo on a woman's arm during a tattoo convention in Ljubljana April 18, 2015. (Photo by Srdjan Zivulovic/Reuters)

A Palestinian woman scuffles with Israeli troops as they demolish sheds belonging to Palestinians near the West Bank village of Yatta, south of Hebron June 19, 2016. (Photo by Mussa Qawasma/Reuters)

Joaldunaks return in a trailer to their town at the end of Carnival between of the Pyrenees villages of Ituren and Zubieta, northern Spain, Monday, February 1, 2016. In one of the most ancient carnivals in Europe, dating from before the Roman empire, companies of Joaldunak (cowbells) made up of residents of two towns, Ituren and Zubieta, parade the streets costumed in sandals, lace petticoats, sheepskins around the waist and shoulders, coloured neckerchiefs, conical caps with ribbons and a hyssop of horsehair in their right hands and cowbells hung across their lower back. (Photo by Alvaro Barrientos/AP Photo)

Finding just the right spot above the clouds at Camp 1 on Ama Dablam, Danuru Sherpa uses his iPhone to catch up with friends and family. Even at 18,500 feet (5,654 meters), climbers here can check their email and other dispatches from the world below. (Photo by Aaron Huey/National Geographic)

Everyone wants to get something for nothing - whether it's a lucky upgrade that means you can turn left when you get on a plane instead or heading off into the economy seats, or even getting a few extra features thrown in for free when you buy a new car.

As some of the sharpest businesses around, no-one understands this quite as well as casinos and that's why they all have a system that they call comps. It's short for "complimentary offers" and these are special treats specially designed to reward you for your loyalty to the casino in question. They're basically bonuses.

A pangolin carries its baby at a Bali zoo, Indonesia, Thursday, June 19, 2014. The pangolin baby was born on May 31. (Photo by Firdia Lisnawati/AP Photo)

Three prostitutes lean out of a window in Santiago, Chile, in an attempt to entice customers inside, circa 1950. (Photo by Three Lions/Getty Images)