The tongue is pretty important.
Without it we would have a hard time speaking, eating, or even breathing.
It's big too. It is constantly moving as it has to keep out of the way of your teeth and has thousands of touch and taste receptors.
But, if it is so important to so many aspects of our lives then why do some of us habitually stick it out of our mouths?
Dr Gillian Forrester, Director of Undergraduate Studies at the School of Science at Birckbeck University, London joins Jonathan to find out why.