Photographic backdrops are used by professional photographers. Backdrops can either be blank or they can have an image on them to make it look as if you are actually at a location, when in fact you are in a studio.
If you have never seen a backdrop, take a walk through any large shopping mall. There are usually photographic stalls where mothers can take their children to have portraits taken. The backdrop is usually clean and white to stop shadows from falling onto faces.
Backdrops are available in a huge variety of materials, colors and sizes. The most popular material for plain or colored backdrops is 100% linen canvas. This is because the light is absorbed more efficiently.
The backdrop is hung onto long poles and sometimes reaches from ceiling height to across the floor where the photographer will be standing. This ensures that only the backdrop is seen by the camera and none of the external room.
For the finished photograph it keeps the illusion alive that what you see in the photograph has actually taken place. Even if the photograph was taken indoors in a small, dark studio.
Remember the old seaside boards where you could stick your head through a hole and on the board would be painted cartoons of musclemen or bathing beauties. They instantly transformed you, for comedy and photographic value, into the cartoon on front. These were backdrops for your face.
Nowadays backdrops are far more sophisticated. The photographer can have you surfing a tidal wave, standing on top of Mount Everest or even walking on the moon.
No matter how wild a location you dream up, photographers will more than likely have a backdrop available for it. If not, there are backdrop specialists who can manufacture the required item on request.
Backdrops are also used in the movie business; especially in films which rely heavily on the use of computerized special effects. More commonly known as "green screen" because the backdrop is green, the actors will be filmed in front of this backdrop and the required effects can be added later by computer.
Think of films such as the Star Wars Trilogy or Jurassic Park, a hefty percentage of filming was undertaken using the green screen backdrop technology. The backdrops are not expensive but the technology required later to add the effects can run into the millions for some Hollywood blockbusters.
When you look at a photograph, remember, the background may be an illusion. Sometimes it's hard to believe out own eyes.