Introduction and Purpose: Phototherapy, involving the therapeutic use of ultraviolet and visible light, has been a cornerstone in dermatology for treating various skin disorders. This review aims to consolidate current knowledge on the mechanisms of action and clinical applications of phototherapy, with a focus on enhancing understanding among clinicians and researchers.State of Knowledge: Phototherapy is particularly effective for chronic conditions such as psoriasis, vitiligo, and atopic dermatitis, where traditional therapies might not suffice. The mechanism involves modulation of immune response and inhibition of cellular proliferation, achieved through various wavelengths, including UVA and UVB. Recent advancements have introduced narrow-band UVB, which offers targeted therapy with fewer side effects compared to broad-band UVB. Moreover, the review explores innovations such as LED-based therapies and photodynamic therapy, expanding the spectrum of phototherapeutic options.Summary: Phototherapy remains a vital and evolving treatment modality in dermatology, offering safe and effective management for multiple skin disorders. Its success hinges on precise application and adherence to treatment protocols. Future research should aim to optimize treatment regimens, reduce side effects, and enhance patient compliance to improve outcomes. By advancing our understanding and application of phototherapy, we can better tailor treatments to meet individual patient needs, thereby improving the quality of life for those afflicted with chronic skin conditions.