I don't know if you saw girls or boys licking their lips when you were watching TV as a child. Generally speaking, when such a picture appears, another person will be attracted to this person. Children, with the nature of imitation, will do this in order to get the attention of others. The more they want to lick, the worse they will become.
Another is chapped lips. There is a red area around people's lips, which is called lip red edge. Its wetness is maintained by abundant local capillaries and a small amount of sebaceous glands. In the cold climate and dry air season, the blood circulation of human skin and mucosa is relatively poor, and sebum secretion will decrease. In addition, if people don't eat much fresh vegetables and don't take enough vitamin B2 and vitamin A, their lips will be dry or even chapped, while people's tongue is moist, and they will feel less dry after licking their lips. However, licking your lips with your tongue can only temporarily moisten your lips through saliva. When the licked lip water evaporates, it will take away more water inside the lip. In addition, saliva contains amylase, mucin and other substances, which are relatively viscous, which will cause connective tissue to contract and lip mucosa to wrinkle, resulting in a vicious circle of "licking more and more dry, licking more and more dry, licking more and more cracked".
So, please take back your tongue, let the child take back your tongue, and get rid of this habit quickly. This habit is very bad.