What's the matter with thick yellow tongue coating?

Tongue coating thick yellow involves two concepts, one is thick, the other is yellow, if you can see the color of tongue through the tongue coating, it is called thin tongue coating, if you can not see the color of tongue through the tongue coating, it is called thick, generally thin tongue, the disease is still relatively shallow, the disease is generally in the surface, but if the tongue coating is thick, the disease has reached the viscera. Yellow normal main heat, if the main heat in the main, combined thick, then the disease has entered, so then see the thick yellow tongue coating, normal refers to the body's viscera inside there is heat evil.