Asked by: John Stark, Uxbridge
If you mean the normal roughness of a healthy tongue, this includes taste buds, and many small, sensitive projections that cover the top surface.
If you mean an additional white or grey furry covering then it’s probably a bacterial or fungal infection such as thrush, and you should get it treated. Healthy tongues are not covered in fur!
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.
