Why Are Newly Built Airplanes Green?

In a world where the majority of aircraft are now painted white, planes with green fuselages are a relatively rare sight. Various exceptions exist in the form of certain military aircraft and those flown by Russian carrier S7 Airlines, but, otherwise, it is a color seldom seen. However, you may have noticed from factory photos that most airliners start off with a green coat of paint, but why exactly is this the case?