The tongue is the fleshy muscle inside the mouth. A tongue lets us taste because the top of the tongue is made mostly of taste buds. It also helps the process of mastication by mixing food with saliva. It is very flexible, so it also helps us eat and talk. The tongue is the strongest muscle in the human body.
Some people can roll their tongue into a tube. The reason why some people are able to and some are not is because of genetic inheritance, meaning that it is based on whether their parents are able to do it. Many schools use tongue rolling as an example of a genetic trait.