Tracy Sarita celebrates the sunrise during the Burning Man 2015 “Carnival of Mirrors” arts and music festival in the Black Rock Desert of Nevada, September 3, 2015. Approximately 70,000 people from all over the world are gathering at the sold-out festival to spend a week in the remote desert to experience art, music and the unique community that develops. (Photo by Jim Urquhart/Reuters)

Mikhail Baburin, 66, talks to his cat Marquis at his house in the remote Siberian village of Mikhailovka, Krasnoyarsk region, Russia, December 5, 2016. Baburin, a former Navy man, barge worker and employee of a military plant in Krasnoyarsk, is the last inhabitant of Mikhailovka, which was founded in the 19th century by migrants from Russia's Mordovia region. He moved in 2000 to Mikhailovka where he was born and has lived there all alone for the last 10 years with only domestic animals. (Photo by Ilya Naymushin/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.

Life as tenant farmers in Kasungu, northern Malawi, can be a struggle for families trapped in poverty, who feel forced to rely on their children’s help, impacting schooling. Here: A tobacco field at a farm in Kasungu region, Malawi. Tobacco is the country’s most important export crop, with tobacco leaf from Malawi filling cigarettes found all over the world. Here: Tiyamike Phiri hopes to become a nurse because she wants to travel the country and help others. (Photo by David Levene/The Guardian)

A woman controls a ball on Ipanema beach in Rio de Janeiro, Brazil, April 14, 2016. As hundreds of thousands of tourists begin descending on Rio de Janeiro for the Olympics that start August 5, the headlines have focused on the street violence, the Zika virus, the water pollution and the rush to finish venues and transport. But Rio, known by Brazilians as the “Marvelous City”, glistens despite it all. The beach is a way of life here. (Photo by Nacho Doce/Reuters)

Christ the Redeemer is seen from the Vista Chinesa (Chinese View) during sunrise in Rio de Janeiro, Brazil, May 4, 2016. Rio de Janeiro is a marvel and a mess all at once. When it hosts the first ever Olympics in South America, starting Aug. 5, visitors will see a city whose stunning topography – stark, verdant mountains loom over packed and playful beaches – competes only with the drama of daily life here. (Photo by Ricardo Moraes/Reuters)

A tattoo artist applying ink on a girl' s arm during the 2017 Moscow Tattoo Festival at Moscow' s Amber Plaza Shopping Center in Moscow, Russia on April 1, 2017. Tattoo artists from all over the world take part in the event. The festival' s program includes a tattoo contest, body taping art marathon, masterclasses, round table discussions and conferences. (Photo by Valery Sharifulin/TASS)