Most people know that not everything you see in a movie or TV show is actually real. Some productions, especially in the sci-fi genre, use a heavy amount of CGI. In order to create a particular spectacle, they use a technique called chroma keying. 

Chroma keying layers images on top of another to create a new image. The way that this is set up is through the use of a green screen. This lets filmmakers create visuals such as space battles and alien worlds without actually having to build them. Here are 35 green screen photos that show how Hollywood really works. 

3Mad Max: Fury Road

Mad Max: Fury Road brought audiences back to the crazy, post-apocalyptic world created in the late 1970s by filmmakers George Miller and Byron Kennedy. Critics were all over this movie when it released, even nominating it for awards, while audiences reacted positively, but not enough to make it a box office hit.

Actress Charlize Theron (who plays Imperator Furiosa) is seen in this photo with green screen material worn like a glove over her hand. This helped animators create her metal arm without having to make her wear a prosthetic piece. Green screens aren’t always used for backgrounds, but serve a variety of purposes.