A male puma, named Bordo arrives for an examination and tests at a veterinary in Brasilia, Brazil, 31 October 2017 (issued 01 November 2017). Bordo, a young male puma, captured when he was a cub, will become the first animal of his species to be released in a sanctuary in the Brazilian savannah in Goias State close to Brasilia. The sanctuary, a preserve for wild cats, is in the first phase and is located on private lands but state funded. (Photo by Joedson Alves/EPA/EFE)

A soldier walks on the bank of the river in central Pyongyang, North Korea on April 16, 2017. (Photo by Damir Sagolj/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.

Two boys in the Gorbals area of Glasgow, UK on January 31, 1948. The Gorbals tenements were built quickly and cheaply in the 1840s, providing housing for Glasgow's burgeoning population of industrial workers. Conditions were appalling; overcrowding was standard and sewage and water facilities inadequate. The tenements housed about 40,000 people with up to eight family members sharing a single room, 30 residents sharing a toilet and 40 sharing a tap. By the time this photograph was taken 850 tenements had been demolished since 1920. Redevelopment of the area began in the late 1950s and the tenements were replaced with a modern tower block complex in the sixties. (Photo by Bert Hardy/Getty Images)

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)

The silhouette of a woman is reflected in a puddle as she crosses a square in front of the Peter and Paul Cathedral in Saint Petersburg on March, 17, 2019. (Photo by Olga Maltseva/AFP Photo)

Men carrying a shrine jump over a bon fire, which means a wish for good luck during a traditional Chinese lunar new year celebration in Jieyang, Guangdong province, China, February 2, 2017. (Photo by Reuters/China Daily)

A boy moves away as a United Nations World Food Programme (WFP) helicopter lands in Rubkuai village, Unity State, northern South Sudan, February 18, 2017. South Sudan on Monday declared famine in some parts of the country, with more than three years of war leaving nearly five million hungry in what aid groups called a “man-made” tragedy. (Photo by Siegfried Modola/Reuters)