Address terms have been studied from different areas, such as sociolinguistics, ethnolinguistics, language learning, and anthropology, with different angles and with varing focus. The same trends apply to the Korean address terms. This study deals with the definition of the term, its applications, their classification and finally their various characteristics. Above all, address terms need to be defined functionally. They are terms which are used to refer to the addressee. Their functions can be classified as follows: 1) to summon attention, 2) to distinguish the intended recipinent of the speaker’s remarks from others who might otherwise consider themselves addressees, 3) to establish or maintain a social relationshiip between the speaker and the addressee(s), and 4) to express the speaker’s attitude or emotion towards the addresee(s). In this respect, we even include zero-form address term in our discution. Further the classification of the terms in Korean and their characteristics are discussed, based on the claim that the criteria for their classification need to be hierarchical and multi-dimensional.