The tongue contributes quite a bit to the functioning of the human body including the ability to taste food and to speak clearly.
It's better to examine your tongue in the morning in natural light before brushing your teeth.
It's recommended to not strain your tongue as it may affect the result.
The color of the coating can vary under the influence of food, beverages, medicines, or smoking. Therefore, to get the right result, examine your tongue an hour or more after any exposure.
Without the tongue we wouldn't enjoy the many flavors of our cuisine, including sweet, salty, sour, bitter tastes.