Damaged train coaches at the site of a train accident, 180 kilometers from Bhopal near Harda district of Mahdya Pradesh, India, 05 August 2015. At least 25 people died when two passenger trains derailed in central India after heavy monsoon rains flooded railway tracks, officials said. Ten coaches from the trains toppled while approaching a small bridge just before midnight. (Photo by Sanjeev Gupta/EPA)

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.

People wearing face masks pose for a photo holding the flag of the Communist Party of China the Museum of the Communist Party of China (CPC) in Beijing, China, 14 October 2022. The CPC museum is a site devoted to permanent and comprehensive exhibitions of the party's history. (Photo by Wu Hao/EPA/EFE)

Picture of a float taking part in the “White Day” parade during the Carnival of Blacks and Whites in Pasto, Colombia on January 6, 2024. The Blacks and Whites carnival has its origins in a mix of Andean, Amazonian and Pacific cultural expressions, and it celebrates the ethnic diversity in the region and was proclaimed by UNESCO as intangible cultural heritage in 2009. (Photo by Joaquín Sarmiento/AFP Photo)

A model wears a creation for Rick Owens' Spring-Summer 2022 ready-to-wear fashion show presented Thursday, September 30, 2021, in Paris. (Photo by Thibault Camus/AP Photo)

An Afghan judge hits a woman with a whip in front of a crowd in Ghor province, Afghanistan August 31, 2015. An Afghan man and woman found guilty of adultery received 100 lashes on Monday in front of a crowd who filmed their punishment, TV footage showed. (Photo by Reuters/Pajhwok News Agency)

Cosplayers dressed as She- Ra and Emma Frost pose for a photograph at the MCM Comic Con at ExCeL exhibition centre in London on October 28, 2017. (Photo by Tolga Akmen/AFP Photo)

Local residents walk past tiger paintings, that marks the upcoming Lunar New Year of the tiger, in front of a department store in Taipei on January 27, 2022. (Photo by Sam Yeh/AFP Photo)