“The Lockheed SR-71 “Blackbird” was an advanced, long-range, Mach 3+ strategic reconnaissance aircraft. It was developed as a black project from the Lockheed A-12 reconnaissance aircraft in the 1960s by the Lockheed Skunk Works. Clarence “Kelly” Johnson was responsible for many of the design's innovative concepts. During reconnaissance missions the SR-71 operated at high speeds and altitudes to allow it to outrace threats. If a surface-to-air missile launch was detected, the standard evasive action was simply to accelerate and outrun the missile”. – Wikipedia

Photo: A U.S. Air Force SR-71A, also known as the “Blackbird”, is put through it's paces during a test flight over Beale Air Force Base in California. The aircraft is a strategic reconnaissance plane by Lockheed and is the world's fastest and highest flying operational aircraft. (Photo by 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 June 1, 2016 photo, Maria Arias stands near her kitchen as she puts on earrings while getting ready for school in Caracas, Venezuela. So many students have fainted from hunger at Maria's school that administrators told parents to keep their children home until they could find more food. (Photo by Ariana Cubillos/AP Photo)

A man dressed in leaves and animals of the forest, the Redeemer on his shoulder, holding the Olympic torch and wearing Olympic rings glasses walks along Copacabana Beach, Rio de Janeiro, Brazil, 31 July 2016. The 2016 Olympic Games start on 05 August. (Photo by Barbara Walton/EPA)

A woman peels potatoes for sale at a market located along a railway line in West Jakarta, Indonesia March 1, 2016. (Photo by Garry Lotulung/Reuters)

Nicki Minaj performs on stage during the 2017 NBA Awards Live On TNT on June 26, 2017 in New York City, USA. (Photo by Michael Loccisano/Getty Images for TNT)

A boy looks for sellable materials close to the burning garbage in the permanent waste land under Sylhet City Corporation for a living, on January 15, 2015. (Photo by Md. Akhlas Uddin/Pacific Press)

“Sunward”. When the Mediterrenean Mantis opened its wings, It seemed very impressive at the sunshine... Photo location: Nicosia, Cyprus. (Photo and caption by Hasan Baglar/National Geographic Photo Contest)