Wood's light (WL) is a useful, economical and easy-to-learn diagnostic tool. Despite its advantages, the use of LW among dermatologists is limited. In porokeratosis, the "diamond necklace" sign has been described, corresponding to the white fluorescence of the hyperkeratotic scale. Subclinical morphea lesions are seen as well-defined dark macules. Among the pigmentary disorders, the bluish fluorescence of vitiligo, the increased contrast of epidermal melasma, and the follicular-centered red fluorescence of progressive macular hypomelanosis stand out. Regarding skin infections, erythrasma presents a coral red fluorescence; tinea versicolor, yellow-green fluorescence; Pseudomonas aeuriginosa, green fluorescence; and scabies, blue-white fluorescence in the acarine burrows. In skin cancer, LW has been used to delimit the surgical margins of both lentigo maligna and non-melanoma skin cancer, with variable results. (c) 2024 AEDV. Published by Elsevier Espana, S.L.U. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).