Graphic Summary by Symbionomics at http://worldbridgerdesign.com/Droppings/symbionomics/images/pattern_cards/rapid_prototyping.png
"The speedy fabrication of sample parts for demonstration, evaluation, or testing. It typically utilizes advanced layer manufacturing technologies that can quickly generate complex three-dimensional objects directly from computer-based models devised by Computer Aided Design (CAD). This computer representation is sliced into two-dimensional layers, whose descriptions are sent to the fabrication equipment to build the part layer by layer. Rapid prototyping includes many different fabrication technologies. Stereolithography (SL), selective laser sintering (SLS), laminated object manufacturing (LOM), and fused deposition modeling (FDM) are a few examples." (http://www.csa.com/discoveryguides/rapidman/gloss.php)
"Rapid Prototyping Machines are like three dimensional printers that turn virtual designs on a computer into solid objects, by building up extremely thin cross-sectional layers, usually some kind of polymer, one on top of the other. Currently they are used mostly in industry to create accurate parts for developmental designs and prototypes. But they are increasingly being used in short manufacturing runs and is known in this circumstance as Rapid Manufacturing. These techniques are sometimes known as [[Solid Freeform Fabrication." (http://www.adciv.org/Rapid_prototyping_machines)
See why here, by Frank Piller:
"I previously used the term "rapid manufacturing" for these technologies. This term should show the evolution from "rapid prototyping". For many years, AF technologies have been used in most cases to quickly build a prototype during a new product development process. Today, however, prototyping is only one of many applications for these technologies. In his posting to the mailing list, Terry discusses what the best term is – and concludes that it should be "3D-Printing". Here are some excerpts (in rearranged order):
- AF processes are being used for a range of applications including concept design and modeling, fit and function testing, patterns for castings, and mold and die tooling. They are also used for fixture and assembly tools, custom and replacement part manufacturing, special edition products, short-run production, and series manufacturing. Prototyping is one of many applications and that's why "RP" is no longer suitable in most instances as a catch-all term. In fact, many companies resist the idea of using a prototyping method for part manufacturing, so using this term could stifle AF's transition to manufacturing applications." 
"Rapid prototyping machines, sometimes called 3D printers, are now commonly used in the design and manufacturing industries for creating solid three dimensional objects straight from CAD models. Currently there are various limitations with these machines but in the near future the price will reduce rapidly, the number of different materials that can be used to make parts will multiply, the resolution will become steadily finer and the build-speed will increase. It is likely that these machines will soon be within the reach of ordinary people following a similar evolutionary path to computer printers. Mail order rapid prototyping services are already available." (http://www.adciv.org/Virtual_designs_into_physical_objects)
"Methodology of Rapid Prototyping
The basic methodology for all current rapid prototyping techniques can be summarized as follows:
1. A CAD model is constructed, then converted to STL format. The resolution can be set to minimize stair stepping.
2. The RP machine processes the .STL file by creating sliced layers of the model.
3. The first layer of the physical model is created. The model is then lowered by the thickness of the next layer, and the process is repeated until completion of the model.
4. The model and any supports are removed. The surface of the model is then finished and cleaned." (http://efunda.com/processes/rapid_prototyping/intro.cfm_
See the Desktop Factory at http://www.desktopfactory.com/