American vedette, burlesque dancer, model, and businesswoman Dita Von Teese performs on the runway during the Alexis Mabille Haute Couture Fall/Winter 2024-2025 show as part of Paris Fashion Week on June 25, 2024 in Paris, France. (Photo by David Fisher/Rex Features/Shutterstock)

A woman cries as she watches the coffin containing the body of Venezuela's late President Hugo Chavez be taken from the hospital, where he died on Tuesday, to a military academy in Caracas, Venezuela, Wednesday, March 6, 2013. Seven days of mourning were declared, all schools were suspended for the week and friendly heads of state were expected for an elaborate funeral on Friday. (Photo by Rodrigo Abd/AP Photo)

A man, right, throws a chair at a business window as another man tries to restrain a woman attempting to stop the damage, after march to City Hall for Freddie Gray, Saturday, April 25, 2015 in Baltimore. Gray died from spinal injuries about a week after he was arrested and transported in a police van. (Photo by Alex Brandon/AP Photo)

British South American Airways hostess Mary Guthrie with a pair of pineapples, on the return of the Lancastrian airliner 'Star Dust' to Heathrow Airport after a test-flight to Buenos Aires, 15th January 1946

A little girl hangs three Siamese kittens on a washing line in a garden in Croydon, London. (Photo by Fox Photos/Getty Images). 14th July 1931

Miss Puerto Rico Stephanie Del Valle (C) reacts after winning in the Grand Final of the Miss World 2016 pageant at the MGM National Harbor December 18, 2016 in Oxon Hill, Maryland. (Photo by Zach Gibson/AFP Photo)

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.

Finding just the right spot above the clouds at Camp 1 on Ama Dablam, Danuru Sherpa uses his iPhone to catch up with friends and family. Even at 18,500 feet (5,654 meters), climbers here can check their email and other dispatches from the world below. (Photo by Aaron Huey/National Geographic)