People hold umbrellas as they walk past a flooded street in Taiyuan, Shanxi Province, China, July 19, 2016. (Photo by Reuters/China Daily)

A man holds an idol of Hindu God Ganesha before immersing it in the Bay of Bengal during Ganesh Chaturthi festival in Chennai, India, Sunday, September 20, 2015. The festival marks the birth of Ganesha who is widely worshiped by Hindus as the god of wisdom, prosperity and good fortune. (Photo by Arun Sankar K./AP Photo)

The Komodo dragon (Varanus komodoensis) was the most popular species overall based on English language Wikipedia page views. It is the world’s largest lizard, living on the islands of Komodo, Rinca and other smaller islands, and on Flores island in Indonesia. (Photo by Eric Nathan/Alamy)

The Royal Castle is seen a veil of heavy winter smog in Budapest, Hungary on January 30, 2017. (Photo by Laszlo Balogh/Reuters)

The moon rising above the Forth Rail Bridge in The Firth of Forth from North Queensferry, England on July 16, 2019. (Photo by South West News Service)

One of the busiest areas in Birmingham, United Kingdom last night was Ludgate Hill in the city's Jewellery Quarter. Brits enjoying the hottest August day for almost 20 years spilled out of packed pubs on August 7, 2020 after sunbathing on beaches around the country as the mercury rose to 36.4C. (Photo by SnapperSK/The Sun)

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.

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)