It is a viral infection caused by the human papilloma virus , which is lodged in the first two layers of the skin (epidermis and dermis). Sometimes they can be mistaken for a callus. Typical symptoms are the appearance of a rough touch lesion, black dots inside the lesion that are small blood vessels (virus vascularization), pain when pinched and not under pressure, although if the wart is covered by a layer of keratin It can cause discomfort when pressed, when walking or simply when standing, and the interruption of dermatomes (normal lines and furrows of the skin). The contagion occurs by direct contact when the skin of the foot, through cracks or wounds, comes into contact with the virus. Treatment consists of deepening the lesion until it is completely eliminated by means of acids, lasers or blistering substances.