Aerial photo taken on April 10, 2022 shows the construction site of Haikou duty-free shopping complex in Haikou, south China's Hainan Province. With a total construction area of about 926,000 square meters, the Haikou duty-free shopping complex project is expected to be officially put into use this year. (Photo by Xinhua News Agency/Rex Features/Shutterstock)

North Korean traffic police women chat next to a residential building while off duty Tuesday, October 18, 2016, in Pyongyang, North Korea. (Photo by Wong Maye-E/AP Photo)

A 180 degrees rotated photograph shows the shadows of Polina (L), a six-year-old Belarusian first grade school girl, and her father, cast on the street while on their way to Polina's first day of school, which marks the traditional start of the academic year, in Minsk, Belarus, 02 September 2019. The start of a new academic year in Belarus, officially called Day of Knowledge, is a festive day for all school and university students in the country. (Photo by Tatyana Zenkovich/EPA/EFE)

Children listen to speakers as U.S. President Joe Biden and first lady Jill Biden host a barbeque with active-duty military families on the South Lawn at the White House in Washington, U.S., July 4, 2023. (Photo by Julia Nikhinson/Reuters)

Alejandro Davidovich Fokina of Spain reacts after the men's single tennis match of Dubai Duty Free Tennis Championship in Dubai, United Arab Emirates on March 01, 2023. (Photo by Amr Alfiky/Reuters)

Lance Sergent Martin Mitchell (R) pins medals to Coldstream Guardsman Martin Hughes in the Tailor Shop in Wellington Barracks on April 20, 2011 in London, England. Soldiers involved in the Royal Wedding of Prince William and Catherine Middleton are preparing their ceremonial duties ahead of the day. (Photo by Oli Scarff/Getty Images)

“Cockayne syndrome (also called Weber-Cockayne syndrome, or Neill-Dingwall Syndrome) is a rare autosomal recessive congenital disorder characterized by growth failure, impaired development of the nervous system, abnormal sensitivity to sunlight (photosensitivity), and premature aging. Hearing loss and eye abnormalities (pigmentary retinopathy) are other common features, but problems with any or all of the internal organs are possible. It is associated with a group of disorders called leukodystrophies. The underlying disorder is a defect in a DNA repair mechanism. It is named after English physician Edward Alfred Cockayne (1880–1956)”. – Wikipedia

Photo: Mother of 12-year-old Chinese girl Sun Yangyang suffering from Cockayne syndrome, tends her at the First Affiliated Hospital of Jilin University on November 11, 2006 in Changchun of Jilin Province, China. The disease results in the senile appearance of Yangyang and also causes eyesight, hearing weakness and other problems. Doctors failed to cure the girl... (Photo by China Photos/Getty Images)

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.