A machine engraves information on an ingot of 99.99 percent pure gold at the Krastsvetmet non-ferrous metals plant, one of the world's largest producers in the precious metals industry, in the Siberian city of Krasnoyarsk, Russia October 24, 2016. (Photo by Ilya Naymushin/Reuters)

People shop at a market ahead of the Lunar New Year in Hong Kong on February 6, 2024 ahead of the Lunar New Year of the Dragon which falls on February 10. (Photo by Peter Parks/AFP Photo)

A priest blesses an elderly Romanian Roma couple after a religious service celebrating the Birth of the Virgin Mary at the Bistrita Monastery in Costesti, Romania, Monday, September 8, 2014. Thousands of Gypsies or Roma gather on a hillside after attending a religious service in a nearby monastery and celebrate the religious holiday by sharing food and playing traditional music until the next dawn. (Photo by Vadim Ghirda/AP Photo)

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.

Somali couple Mohamed Noor (L) and Huda Omar pose for a photograph at their makeshift home during their wedding ceremony in Mogadishu's Rajo camp, Somalia August 17, 2016. Having met two years ago, the pair have just married at Rajo camp, where some 400 families live. Most, like Noor's parents, came here in the early 1990s to flee famine. (Photo by Feisal Omar/Reuters)

Human like robots and robotic faces that mimic human expressions are displayed at the annual World Robot Conference at the Beijing Etrong International Exhibition and Convention Center in Beijing, Wednesday, August 16, 2023. (Photo by Ng Han Guan/AP Photo)

Italy's Arianna Valcepina falls during the women's 500 m qualifying race at the ISU Short Track Speed Skating World Cup in Gdansk, Poland, 16 February 2024. (Photo by Adam Warzawa/EPA)

A man does physical exercise during sunset over the Finnish Gulf coast in St. Petersburg, Russia, Wednesday, April 14, 2021. (Photo by Dmitri Lovetsky/AP Photo)