What could it mean if you have a white patch on your tongue?

Yeast infection: Could be oral thrush (yeast infection), leukoplakia which is an early precursor to oral cancer, or lichen planus (an inflammatory disorder which may affect only the mouth or other parts of the body). It needs to be examined by a dermatologist or dentist for possible treatment.

Few possibilities : Could be a fungal infection, biofilm, layers of old tissue. Your dentist or physician can determine the cause easily, please seek their help.

A few things...: Leukoplakia which only means white patch and can be precancerous or cancerous, oral candidiasis or thrush which is a fungal infection, lichen planus which has several forms and of unknown origin. In any case, the only way to know for sure is to see a dentist or oral surgeon for a diagnosis, possible biopsy and treatment if appropriate.