Ready to Fly (or RTF) is a term used to describe radio controlled airplanes or radio-controlled helicopters that are supplied fully built with no assembly required.
So-called "toy R/C" airplanes of the type distributed by companies like Air Hogs almost always fall under the category. However, there are models available for varying skill levels. Advanced helicopters under this category are test flown at the factory and are claimed to be able to fly "out of the box." [1]