Phototherapy, also known as light therapy, is a technique used in nail art to create embossed designs. It involves using light to cure a gel or resin that forms the pattern on the nails. For beginners, there are various online tutorials and courses available to learn the basics of this technique, which includes selecting the right light, choosing embossing powders, and applying them to the nails. Images of nail designs created using phototherapy can serve as inspiration and guides for those starting out.