Leukoplakia is a white patch or plaque that develops in the mouth and cannot be wiped away. It affects 1.5-12% of the population, usually those over age 40, and prevalence increases with age. Leukoplakia has various clinical forms and ranges in appearance from flat and uniform to raised or irregular patches. A biopsy is needed to examine the tissue for signs of dysplasia or oral cancer. While most leukoplakia is harmless, some may develop into cancer over time, so prevention focuses on lifestyle changes like quitting smoking and reducing alcohol.