what is a green screen
Green screen (also blue screen) is the use of a single color as a backdrop in filming to make it simpler and easier to add backgrounds, characters or other images. The pure, uniform green or blue color is easily taken out of the resulting visual content with automatic software color selection and removal tools and the desired background inserted in its place. Green and blue screens are most commonly used, although any color could work in the same way. Bright green is often chosen because it's not a color that people wear very often. One familiar use of green screens is to add maps to the background in weather reporting, behind meteorologists.