Stereolithography (SLA) is also known as optical fabrication , is a form of 3D printing technology which is used for preparing a prototype in a layer by layer fashion using photochemical processes by which light causes chemical monomers and oligomers to cross-link together to form polymers. Those polymers then make up the body of a three-dimensional solid.
In SLA technique photo polymer resin(namely clear resin , castable resin, standard resin) is used as build material. In this technique, the build material will be in liquid state. This resin is cured,layer by layer accordingly by the laser that is beamed.