A woman in a Cholita dress poses for photos, at the Uyuni Salt Flat in Bolivia on March 26, 2022. (Photo by Claudia Morales/Reuters)

A reveller performs while attending the block party “Galo da Madrugada” during carnival festivities in Sao Paulo, Brazil on February 25, 2020. (Photo by Rahel Patrasso/Reuters)

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.

“Grit and Glamour”, a retrospective of the late British photographer Elsbeth Juda, who fled Nazi occupation and came to England in 1933, is at the Jewish Museum, in London, until July 1, 2018. Here: Shelagh Wilson, Copacabana beach, Rio de Janeiro, 1951. (Photo by Elsbeth Juda Archive/Victoria and Albert Museum)

Tournament officials use golf carts to coax an alligator off of the 17th fairway and back into the water during the third round of the PGA Zurich Classic golf tournament at TPC Louisiana in Avondale, La., Saturday, April 24, 2021. (Photo by Gerald Herbert/AP Photo)

Runner-up; Hon Yen marine ecosystem. Phu Yen, Vietnam. Every year between May and August, the coral of this rich and diverse ecosystem becomes exposed at low tide. (Photo by Truong Hoai Vu/Royal Society of Biology Photography Competition)

MSP Ash Regan and Lexie take part in Holyrood Dog of the Year on June 26, 2023 in Edinburgh, Scotland. At the annual contest, jointly organised by the Kennel Club and Dogs Trust, members of the Scottish Parliament compete with their dogs and Dogs Trust rescue dogs for the title of “Holyrood Dog of the Year”. (Photo by Jeff J. Mitchell/Getty Images)

A surfer is seen during sunset at Pacifica State Beach in Pacifica, California, USA on August 6, 2023. (Photo by Tayfun Coskun/Anadolu Agency via Getty Images)