Blue Light Therapy, also known as photodynamic therapy (PDT), was first introduced in the late 1990s as a promising treatment for various skin conditions. The therapy involves the application of a photosensitizing agent, typically aminolevulinic acid (ALA) or methyl aminolevulinate (MAL), to the skin, followed by exposure to a specific wavelength of blue light (415-495 nm). The photosensitizer is selectively absorbed by abnormal or precancerous cells, and when activated by blue light, it generates reactive oxygen species that destroy the targeted cells while leaving healthy tissue unharmed.