There are all shapes and sizes of RC airplanes out there, and they're available for purchase at different levels of completion:
RTF (Ready to Fly) planes typically require the least amount of time and effort to get the plane flying. A true RTF will include the assembled airframe, with the power system and radio equipment already installed. The work required to get an RTF out of the box and into the air typically involves attaching the wing (possibly the tail as well) and charging the battery or adding fuel.
ARF (Almost Ready to Fly) are more involved than RTF's to prepare for flight and can require anywhere from 2 hours up to 20 hours of assembly time for the larger ones. When you open the box an ARF comes in, you can expect to find several completed and covered components that must be assembled. An ARF is most often, but not always, sold without a motor/engine or radio gear. In addition to assembling the airframe, the modeller must select and install their own power system and radio gear.
Kits require much more time, energy, and care to complete. When you purchase a kit, you will most likely receive: all of the balsa and lite-ply wood to complete the airframe, possibly some molded plastic or fiberglass parts, a limited amount of hardware, decals, and a set of plans. Depending on the size & type of airplane and level of finish desired, completing a kit can take anywhere from 20 hours to several hundreds of hours to complete.
Electric or Glow/Gas?
Unless you're going to start out with an unpowered sailplane, you will need to decide what type of motive power to use--electric or wet fuel. Both power sources have their advantages and disadvantages, but you should choose what works best for you.
