Women take photos on Lake Salt, which is on the UNESCO World Heritage Tentative List, during the sunset in Ankara, Turkiye on July 3, 2023. Lake Salt, which is one of the important wetlands of Turkiye and is of great importance for the protection of biological diversity in our country, also attracts the attention of visitors. (Photo by Aytac Unal/Anadolu Agency via Getty Images)

Displaced girl looks on behind a tree outside a school turned into shelter, amid ongoing hostilities between Hezbollah and Israeli forces in Baabda, Lebanon on October 31, 2024. (Photo by Yara Nardi/Reuters)

A person takes a photograph of a 60-foot-long balloon of Kim Kardashian to promote SKIMS Swimwear in Times Square in New York City, U.S., March 4, 2025. (Photo by Adam Gray/Reuters)

Miss Colombia Ariadna Gutierrez, right, and Miss Philippines Pia Alonzo Wurtzbach wait for the announcer to name the new Miss Universe at the Miss Universe pageant on Sunday, December 20, 2015, in Las Vegas. Gutierrez was incorrectly crowned before Wurtzbach was named Miss Universe. (Photo by John Locher/AP Photo)

Growing cities, overuse of fertilizers and factory wastewater have degraded China's water supplies to the extent that half the nation's rivers and lakes are severely polluted. China aims to spend $850 billion to improve filthy water supplies over the next decade, but even such huge outlays may do little to reverse damage caused by decades of pollution and overuse in Beijing's push for rapid economic growth. Photo: Fishermen row a boat in the algae-filled Chaohu Lake in Hefei, Anhui province, June 19, 2009. (Photo by Jianan Yu/Reuters)

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.

Animal rights activists covered with fake blood sit on the floor during a protest against the use of animals in research to mark World Day for Animals in Laboratories in central Madrid April 24, 2014. The sign reads, “How many rabbits do your shampoo kill?”. (Photo by Andrea Comas/Reuters)

Palestinians scuffle with Israeli forces at Damascus Gate in Jerusalem's Old City on December 8, 2017. Palestinians clashed with Israeli security forces after calls for a “day of rage” as US President Donald Trump's declaration of Jerusalem as Israel's capital sent shockwaves through the region for a second day. (Photo by Thomas Coex/AFP Photo)