The 3D stands for three dimensional.
This is a printer that can create 3D objects such as prototype parts or anything else that someone cares to make. More formally, this kind of process is called 'additive manufacturing' but that does not sound so interesting as '3D printing'.
There are a number of printer technologies that can create 3D shapes. For example, one uses a vat of liquid that solidifies locally when heated. A hot laser beam scans the surface to create a very thin solid surface, then that solid layer is dropped slightly below the liquid surface so a fresh batch of liquid flows above it, then the laser scans and creates another solid layer. So very slowly, a solid object emerges.
It is only recently that 3D printers have come to the public eye, but they have been around for twenty years or more. Then, they had the horrendous name of stereo-photolithography machines and were extremely expensive. They were \ are used in the car industry to make prototype parts during development.
What has happened is that the printers have come down in price so people other than large corporation workers can afford one.
Also computing power has also come down in price so the 3D CAD file that drives the printer can be calculated and created at lower cost.
Objects can be produced from more than a hundred different materials including plastic, nylon even metal depending on what printer technology is used.
Challenge see if you can find out one extra fact on this topic that we haven't already told you
Click on this link: What is a 3D Printer