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.

This picture taken on July 25, 2014 shows people cooling off in a waterpark in Suining, southwest China's Sichuan province. Meteorological departments issued an orange alert for high temperature as a heat wave embraces Sichuan province, with temperature of most area topped 37, local media reported. (Photo by AFP Photo)

Nicaraguan army members carry a participant playing the role of a victim during a national multi-hazard drill organized by the National System for Prevention, Mitigation and Attention to Disasters (SINAPRED), in the 30 de Mayo neighborhood in Managua, Nicaragua, September 26, 2016. (Photo by Oswaldo Rivas/Reuters)

German flying ace Baron Manfred von Richthofen (1892–1918) also known as The Red Baron with his dog Moritz, circa 1916.

Cannabis had already dominated the world of medicine. More and more people become convinced of its effectiveness, especially in terms of treating known diseases (e.g., Epilepsy, Depression, and Anxiety). Such commotion resulted in several experts to create and establish pieces of research about cannabis. Factors affecting the pros and cons are identified and verified to know further whether or not it is a capable substance.

For France, the trauma of the Algerian War (1954-1962) was not unlike the experience of the Vietnam War for the United States. But, unlike the conflict in Vietnam, few photographic documents exist from that period in Algeria: it is as if the French responded with collective amnesia. Marc Garanger’s Algerian Women is one of the few photographic essays dedicated to that painful period... Photo: A 1960 photograph of an Algerian woman in a French regroupment village. (Photo by Marc Garanger)

In this Saturday, March 3, 2018, photo, a contestant gets ready to throw a hatchet at a wooden bull's-eye at the Kick Axe Throwing venue in the Brooklyn borough of New York. Kick Axe Throwing is the first bar in New York City to pick up on a nationwide trend of ax throwing, a growing sport that some enthusiasts hope will take off the way bowling did in the last century. (Photo by Mary Altaffer/AP Photo)

With a presence in nearly every city and town across Iran, the paramilitary Basij volunteer corps has an ever-increasing influence on life in the Islamic Republic. Authorities created the Basij, which means mobilization in Persian, just after the country's 1979 Islamic Republic. It is part of Iran's powerful Revolutionary Guard. Photo: In this Thursday, August 22, 2013 photo, a female member of the Basij paramilitary militia aims a rifle as a trainer looks over her shoulder in Tehran, Iran. (Photo by Ebrahim Noroozi/AP Photo)