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)

People in Kathmandu joke that the face mask has now become part of the national dress – an indispensable accessory in an effort to protect themselves from the dust. Nepal has the worst air quality in the world, according to the Environmental Performance Index. (Photo by Pete Pattisson/The Guardian)

A cat is presented during “The "3rd International Pursaklar Cat Beauty Fest”, on October 14, 2018 in Ankara. (Photo by Adem Altan/AFP Photo)

People walk under Australia's iconic landmark Harbour Bridge in Sydney on April 3, 2019, as heavy fog blankets the city. Low visibility due to heavy fog affected traffic in the city and caused flight delays at the Sydney airport. (Photo by Saeed Khan/AFP Photo)

A prototype of the Space Exploration Technologies Corp. (SpaceX) Starship launch vehicle stands during an event at the SpaceX launch facility in Cameron County, Texas, U.S., on Saturday, September 28, 2019. Elon Musk gave space fans an update Saturday evening on the status of “Starship”, the next-generation vehicle his SpaceX plans to use to eventually take humans to Mars. (Photo by Callaghan O'Hare/Reuters)

A double rainbow is seen above a woman holding an umbrella and selling snacks along the road in Siaya county, Kenya on May 3, 2020. (Photo by Thomas Mukoya/Reuters)

A woman enjoys the sun at Plaka beach on the Aegean island of Naxos, Greece, Friday, May 14, 2021. Greece launched its tourism season Friday amid a competitive scramble across the Mediterranean to lure vacationers emerging from lockdowns. (Photo by Thanassis Stavrakis/AP Photo)