Chroma key compositing, or chroma keying, is a visual effects / post-production technique for compositing two images or video streams together based on color hues. A green screen allows filmmakers to superimpose anything or anyone into a photo or video.
A few of my favorites...
Disney's Frozen is the biggest blockbuster in the history of animation. Girls all over the world are singing "Let it go" as they dress up as Disney characters. Using green screen technology your daughters poses in front of a green screen. Judy Burton has created a number of frozen wonderland overlays. These overlays, which sandwich the girls image between a background and a foreground, will make the girls feel like they are in a magic place. Nothing is more satisfying than hearing giggles of delight when the girls see themselves in these wondrous settings.