Abbreviation is one of the typical examples of using language. Traditionally, abbreviations are classified into the following four major categories in English morphology: (i) initialism, (ii) acronyms, (iii) clipping and (iv) blending. This research examines types of abbreviatory expressions in Korean from a sociolinguistic perspective. This study first provides a brief analysis of types of abbreviations in Korean, mainly in terms of morphology. The examination shows that in Korean the distinction between initialism and acronym does not hold because of the nature of the syllable-based writing system of Korean, and that acronym is the most widely used types of abbreviation. Second, the study discusses linguistic motivations which are at work in the formation of abbreviations mainly in terms of economic motivation and motivation of distinctiveness. Third, this research explores conditions on the use of abbreviations in terms of sharedness of the information about the referent being talked about. It also shows the property of exclusiveness in the sense that members of a certain speech community share the meanings of the abbreviations. In addition, it explores functions of abbreviations in the following terms: maintaining solidarity, excluding outsiders, novelty, temporariness, and so on. Finally, this paper shows that not only a morphological approach but also a sociolinguistic perspective is necessary in order to fully account for the formation and use of abbreviations in language.