Seborrheic keratosis is one of the most common skin tumors. Because this tumor is benign, treatment is not mandatory. However, the lesions are often removed especially for cosmetic reasons. Despite its frequency, many aspects of seborrheic keratosis remain elusive. In the last years new molecular genetic insights into seborrheic keratoses have been gained. The current knowledge about seborrheic keratosis with respect to epidemiology, pathogenesis, diagnosis and therapy is summarized.