The present author suggests a typology of approaches to the study of slang. Lexicographic, grammatical (word-forming), and communicative approaches are differentiated. In the studies on slang, the three approaches are not equally represented. The lexicographic approach dominates, often complemented by grammatical or word-formation analyses. The communicative approach to the study of slang is still in its infancy.
Most works on slang seem to start tacitly from the pre-supposition that the individual lives only in one social milieu (environment, setting) and thus masters only one slang. This misconception may arise since slang is often understood as a thematically relatively homogeneous set of substandard lexical units taken out of the communicative process. However, it is clear that an individual uses elements of several types of slang. For example, today's student may be also a sportsman or a hiker or a musician etc. It follows, that one should be faced not only with the problem of describing abstract individual types of slang but also the way they interact in discourse, in other words, with their intersections.
In stating that today's student may also be a sportsman, a hiker or a musician, one is pointing to the synchronic state of his personality. The individual, however, in various stages of his life develops and passes through various social milieus, which can be seen in the language he uses. It follows that the individual in various stages of his life masters various types of slang.
Social milieus and thus also types of slang can be divided into two groups: obligatory social milieus, i.e. such that the individual has to pass through, and facultative ones, i.e. such that he need not go through. Obligatory social milieus and thus obligatory types of slang, i.e. those the individual has to learn to be integrated normally into society, may have a relatively great influence on the core of a national language. Among obligatory types of slang it is necessary to include the slang of pupils, students, and for a substantial part of the male population military slang.
Obligatory types of slang have one interesting and essential property which maintains their influence. This is that in the course of his life an individual is in contact with a particular obligatory slang in principle at least twice: the first time by his direct participation in a given social milieu and the second time through the mediation of his children, as for them too the "passage" through a given social milieu is of course obligatory.
In accordance with the Czech linguistic tradition, slang may be defined as "an integral part of the national language in the form of a substandard stratum of specific naming units, adopted in day-to-day (most often in semi-official and unofficial) communication among people limited to the same working milieu or to the same sphere of interest; it serves partly the specific needs of language communication, and partly as a means of expressing affiliation to a certain social milieu" (J. HUBÁCEK). An analysis of slang as one of a number of expression (semiotic) systems of a particular social milieu as well as the study of the correlation of these systems seems to be worth pursuing. This way, studies on slang could also contribute to a better knowledge of particular subcultures.