There are four main types of 3D printers: Fused Deposition Modelling (FDM), Stereolithography (SLA), Selective Laser Sintering (SLS), and Digital Light Processing (DLP). FDM is the most common type of 3D printer and is used to create objects layer by layer. SLA uses a laser to harden resin, while SLS and DLP use lasers to sinter powdered materials. Each of these technologies has its own pros and cons, so make sure to do your research before choosing the right 3D printer.