It doesn't get any more basic, or more complicated than the Flatbed truck. It can be ordered as just a plain platform (normally with a headboard), or you can modify it in a thousand ways to make it more useful to you or your end user.
The most basic option to add is gates (some say stakes, or racks). We can then call it a stakebed. Then we can just accessorize it as much as we want: Liftgates, Underbed boxes, More Underbed Boxes (along the whole side if you like), Upper Bed Boxes, Steel Floor, Steel Overlay (smooth or diamond plate), Cargo Tie Downs, Tool Holders, Tapered Headboard, HD Rack (that's why we call them gates I suppose. . .), Dump Hoist, Gooseneck hitch or 5th wheel hitch, Solid Side Gates in wood or steel, Swing-Away Rear Gate Assembly, Hitch, and on and on and on. It is simply one of the most modified bodies available. We add a few things and we can call it a Contractor Body since a Contractor Body is just a flatbed with accessories. Then there is the Gooseneck Body which is a diamond plate steel deck flatbed about 1/2 a foot shorter than the normal flatbed and it comes with a gooseneck hitch opening and is very popular with Ranchers and Farmers.
Flatbeds are available in any length needed for the user, but the most common sizes are 8' and 9' for single rear wheel trucks, 9', 10', 12', 14' and 16' for most dually trucks. The 10' and 12' are the most popular of all and of those two, the 12' is hands down the favorite stocking model.
The Flatbed: It's like a blank canvas
Commercial Truck Success www.comtrk.com or www.commercialtrucksuccess.com