Infixation is a very distinctive and an easily recognizable morphological process where an affix (which is called an infix) is inserted in the middle of a word. It differs from some other morphological processes in that it is a great deal more flexible and not strictly susceptible to many rules. There are, of course, many characteristics which are specific and distinctive and, in a way, canonical for this kind of process. However, infixation is also known for the set of irregular characteristics it has. The main purpose that infixation serves in morphology is not the formation of new words or meanings of words, but the one of stylistic and expressive manner, such as expressing humour, obscenity, vulgarity, the affiliation to a certain group of people, their habits, culture, language. This paper is concerned with what infixation actually is and how it is formed with regard to both its history and the modern period of time. The emphasis is put on the four most recognizable types of infixation: expletive infixation, diddly-infixation, Homeric infixation and iz-infixation. Each of them is exemplified and illustrated in detail, denoting where and in which way they are most frequently used. The paper is divided into four main chapters, describing infixation and its characteristics in general, types of infixation, and its popularity and representation over the world.