According to the dictionary, to kiss means to touch or oppress someone or something with a movement of the lips as an expression of love, desire, reverence, or as a greeting. Filematology is the unofficial science that studies kisses and investigates their origins, their meaning, the different types of kisses, the physical and mental reactions it provokes. The theory about the origin of the kiss says that it is a practice typical of humanity and arose as a result of breastfeeding or when babies had to be fed through the mouth.