A wide-angle view shows the ascent of the shuttle Challenger on January 28, 1986. In the seconds after ignition, the rocket engines' hot blast began the process of destruction. (Photo by NASA)

A woman gets a throat swab during a public COVID testing outside a shopping mall on Sunday, May 22, 2022, in Beijing. (Photo by Andy Wong/AP Photo)

Honey bees and ground bumblebees fly with thick purple pollen pouches to the flower of a corn poppy, also called poppy or corn rose, to obtain nectar in Berlin, Germany, Tuesday, June 7, 2022. Bumblebees, which like bees belong to the stinging bee family, form so-called summer colonies that exist for only a few months. (Photo by Wolfgang Kumm/dpa via AP Photo)

A competitor competes during the Hortobagy Hobby Horse Cup in Tiszafured, Hungary, on October 26, 2024. (Photo by Bernadett Szabo/Reuters)

Tomoka Miyazaki of Japan hits a return against Lin Hsiang-Ti of Taiwan in their women's singles quarter-final match during the Hong Kong Open badminton tournament in Hong Kong on September 12, 2025. (Photo by Peter Parks/AFP Photo)

Hollywood actress Malin Akerman helps King Digital Entertainment set the Guinness World Record for the World's Largest Hammock to celebrate the launch of its new game Paradise Bay on Wednesday, September 2, 2015, in Jersey City, N.J. (Photo by Charles Sykes/Invision for King World Entertainment/AP Images)

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.

Mara Salvatrucha (MS) gang members show off their weapons in the Las Victorias district of San Salvador. In March 2012, the two largest gangs in El Salvador - the Mara Salvatrucha (MS) and the Barrio 18 (M18) - agreed on a truce following secret negotiations between gang leaders in prison which were mediated by a bishop and a former rebel leader. It is unclear whether the decision was the idea of the gangs themselves or whether they were encouraged by the government. (Photo by Adam Hinton)