Nasoin Akhter, 15, has her makeup done at a beauty parlor on the day of her wedding to a 32-year-old man, August 20, 2015, in Manikganj, Bangladesh. In June of this year, Human Rights Watch released a damning report about child marriage in Bangladesh. The country has one of the highest rates of child marriage in the world, with 29% of girls marrying before the age of 15, and 65% of girls marrying before they turn 18. (Photo by Allison Joyce/Getty 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.

In this September 14, 2017 photo, young women pose for a photo inside their squatter building that used to house the Brazilian Institute of Geography and Statistics (IBGE) in the Mangueira slum of Rio de Janeiro, Brazil. Many lower-middle class Brazilians who gained ground during the boom years have since slid back closer to the poverty line. (Photo by Felipe Dana/AP Photo)

The three orangutans at Pairi Daiza zoo, Belgium, developed a “special bond” with the otters after their river was run through the ape enclosure on March 2020. The zoo said it enriched both species’ environments. An animal – and this is even more the case of orangutans, with whom humans share 97 per cent of their DNA – must be entertained, occupied, challenged and kept busy mentally, emotionally and physically at all times. (Photo by Pascale Jones/The Sun)

A young woman poses for a selfie at Red Square which is under preparations for the Victory Parade during sunset in Moscow, Russia, Monday, April 26, 2021. Russia will celebrate celebrate 76 years of the victory in WWII on May 9, 2021. (Photo by Alexander Zemlianichenko/AP Photo)

Filipino children play at a fishing village along the coast of Manila Bay, Philippines, 30 May 2023. As a precaution of approaching Typhoon Mawar, Philippine government authorities have evacuated thousands of residents, imposed a no-sail ban, suspended school classes, and shutdown offices in the northern part of Luzon island, the country's largest and most populous island. (Photo by Francis R. Malasig/EPA/EFE/Rex Features/Shutterstock)

Women breastfeed their babies at an event promoting the freedom of mothers to breastfeed in public, during World Breastfeeding Week, at the Village Museum in Bucharest Romania, Saturday, August 6, 2016. (Photo by Andreea Alexandru/AP Photo)

The secretive indri (Indri indri) of Madagascar, the largest living lemur. It is also critically endangered and highly evolutionarily distinct with no close relatives, which makes its branch one of most precarious on the mammal evolutionary tree. In the likely event that the indri goes extinct, we will lose 19m years of unique evolutionary history from the mammal tree of life. (Photo by Pierre-Yves Babelon/Aarhus University)