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 kingfisher dives into the leafy water of the River Alde near Rendham, Suffolk in the second decade of November 2022 and catches two fish. Kingfishers must be able to see the fish they want to catch before making their dive, so for this bird to be successful when leaves covered the surface of the water shows its true skill for survival. (Photo by Ivor Ottley/Animal News Agency)

A young trumpeter joins the Anglican Church band as the coffin of late Archbishop Emeritus Desmond Tutu arrives outside the St. George's Cathedral in Cape Town, South Africa, 31 December 2021. The anti-apartheid leader and Nobel Peace Prize laureate, who was a key figure in the dismantling of apartheid, died on 26 December 2021 at the age of 90. A full state funeral will be held on 01 January 2022. (Photo by Nic Bothma/EPA/EFE)

In this photo taken Tuesday, June 23, 2015, a Ukrainian serviceman from the Kiev-2 volunteer battalion fires an weapon at a frontline in the village of Krymske, east Ukraine. Few places along the front line in east Ukraine see regular fighting as bitter as the village of Krymske. For now, Krymske is in the hands of Ukrainian government forces and the volunteer battalions that fight alongside them. (Photo by Evgeniy Maloletka/AP Photo)

Josef Stalin's head is left in a Budapest street after a statue to the communist dictator was torn from its plinth during the Hungarian Revolution in 1956. (Photo by Robert Hofbauer/Radio Free Europe/Radio Liberty)

Listed as endangered on the IUCN red list of threatened species, a humphead wrasse, or Napoleon fish, swims in an aquarium during an event in Tokyo's shopping district of Ginza on August 5, 2019. (Photo by Kazuhiro Nogi/AFP Photo)

Two styles of cleaned bird's nest, Yan Zhan (L) and Su Zhan (R) await repacking at a processing plant in Kuala Lumpur, February 17, 2015. Prized in China for is alleged health benefits for hundreds of years, nests made from swiftlets' saliva are being mixed into coffee and cereal as the Southeast Asian producers of the delicacy seek to broaden its appeal, and their profit margins. The nests are among the world's most expensive foods, selling for up to $2,500 a kg and the swiftlets that weave them are indigenous to Indonesia, Malaysia, Thailand and Vietnam. (Photo by Olivia Harris/Reuters)