Kissing in history has been used as a respect. The Roman emperors had given importance to those who were against them, with the parts of their bodies that they allowed them to kiss. They allowed the important people kiss their lips, less important ones to kiss their hands. Also, They allowed people who didn't care kiss their feet. The slaves were only able to kiss the land where the emperor pressed his feet.
In human history, the use of kissing as an expression of love is fairly new. The pioneer of the adult opposite sex kissing each other is French in the sixth century. So, The French kiss statement came from here.
Even people who give importance to oral health are known to kiss 250 virus and bacteria each other while kissing their lips. About 29 facial muscles are stretched and relaxed, 15 calories are spent, also cell regeneration is accelerated while kissing. The most importantly, it is suggested that kissing can be accepted as a natural treatment method through spiritual relaxation.