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.

A humanoid robot works side by side with employees in the assembly line at a factory of Glory Ltd., a manufacturer of automatic change dispensers, in Kazo, north of Tokyo, Japan, July 1, 2015. Japanese firms are ramping up spending on robotics and automation, responding at last to premier Shinzo Abe's efforts to stimulate the economy and end two decades of stagnation and deflation. (Photo by Issei Kato/Reuters)

Central Bangkok and the Chao Phraya River are seen from an abandoned skyscraper in Bangkok April 19, 2015. The abandoned building, known as Satorn Unique, dubbed the “ghost tower” was destined to become one of Bangkok's most luxurious residential addresses but construction was never completed as the Thai economy was hit during the 1997 Asian Financial Crisis. Now, many travellers visit and explore 49-storey skyscraper. (Photo by Athit Perawongmetha/Reuters)

The sign above the door of restaurant and hotel “Am Paulusbogen” is partially submerged in the flooded centre of the Bavarian town of Passau, about 200 km (124 miles) north-east of Munich June 3, 2013. (Photo by Michaela Rehle/Reuters)

Ultra Orthodox Jewish men watch a bonfire during the Jewish holiday of Lag Ba-Omer in Jerusalem's Mea Shearim neighbourhood April 27, 2013. Israelis celebrate the Jewish holiday of Lag Ba-Omer, which marks the end of a plague in the Middle Ages that killed thousands of disciples of a revered rabbi in the holy land, by lighting bonfires across the country. (Photo by Ronen Zvulun/Reuters)

It looks like an underwater tornado, but a diver was actually stuck in the middle of a huge school of fish. The fish swarmed around Mika Woyda in their thousands as she swam off the coast of Cabo Pulmo, Mexico. Her husband Caine Delacy snapped the breath-taking images of Mika in scenes he revealed he had never witnessed in 20 years of diving. Before entering the water the couple, who live in Boulder, Colorado, had some shots in mind but never imagined what they would capture. Here: photographer Caine Delacy with his wife Mika Woyda. (Photo by Caine Delacy/Mika Woyda/Caters News)

A worker paints the Amazon Tall Tower Observatory (ATTO) in Sao Sebastiao do Uatuma in the middle of the Amazon forest in Amazonas state January 10, 2015. The Amazon Tall Tower Observatory is a project of Brazil's National Institute of Amazonian Research and Germany's Max Planck Institute and will be equipped with high-tech instruments and an observatory to monitor relationships between the jungle and the atmosphere from next July. According to the institutes, ATTO will gather data on heat, water, carbon gas, winds, cloud formation and weather patterns. (Photo by Bruno Kelly/Reuters)

A model presents a creation from Dior's Cruise 2021 collection during a live-streamed runway show without an audience due to the coronavirus disease (COVID-19) outbreak, at the Piazza del Duomo, in Lecce, Italy on July 22, 2020. Christian Dior hosted a live but audience-free fashion show in the Italian city of Lecce, in a dazzling celebration of local crafts and traditions that included a dance spectacle in the middle of the baroque main square. (Photo by Alessandro Garofalo/Reuters)