Stereolithography or SLA is one of the earliest 3D printing technologies and one of the most versatile. It builds parts layer by layer from a photocurable resin. A high powered UV laser is focused onto the build platform to cure the material one layer at a time.
SLA offers a range of material options and provides parts with great accuracy to CAD and a good surface finish. The parts need to be built with support structures which are removed post process. SLA is a good option for prototypes and low volume production.