Princess Elizabeth with her husband Prince Philip Duke of Edinburgh and their children Prince Charles and Princess Anne. (Photo by Keystone/Getty Images). August 1951

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 family takes a picture at the Oscar Myer Wienermobile during a visit to “The Flower Fields”, as California opens up from the pandemic, in Carlsbad, California, U.S., March 31, 2021. (Photo by Mike Blake/Reuters)

Festivalgoers are seen during the 2019 Coachella Valley Music And Arts Festival on April 20, 2019 in Indio, California. (Photo by Emma McIntyre/Getty Images for Coachella)

Some bats in the forested area of Guapiles, Costa Rica, 21 April 2020. (Photo by Jeffrey Arguedas/EPA/EFE)

A policeman aims his weapon in Istanbul, Turkey July 16, 2016. Members of Turkey's armed forces said they had taken control of the country Friday as explosions, gunfire and a reported air battle between loyalist forces and coup supporters erupted in the capital. President Erdogan remained defiant and called on people to take to the streets to show support for his embattled government. (Photo by Kemal Aslan/Reuters)

This photo taken on November 6, 2023 shows people posing for photos next to the statue of “Hachiko” in front of Shibuya station in central Tokyo, ahead of the 100th anniversary of the legendary dog's birth this month. A century since its birth, the tale of the loyal companion who had waited at the Shibuya train station for its master to come home – not knowing he had already died – continues to inspire the public, who have made the statue a singular landmark at a glitzy hub of Tokyo's street culture. (Photo by Richard A. Brooks/AFP Photo)