The most common are SLA (Stereolithography) and DLP (Digital Light Processing). SLA represents the first 3D printing technology in history. It was invented in 1986 by Chuck Hull. With the help of mirrors on the X and Y axes, the light source penetrates through a container with resin, which selectively hardens in layers.
SLA is a slightly more accurate method, as it uses a laser to work more pointwise, making it more suitable for printing smaller pieces, while DLP uses a projector that has a wider beam of light. In this way, the piece is made faster, but not with such precision, so this method is used to make larger pieces.