The main goal of this paper is to look over the current extension of topic studies in linguistics. Admitting that the definition of topic still remains a controversy among scholars, much of research has been done so far. The difference in their approaches voice the various reflections in theoretical pursuit. Among others, the present study focuses on the well-known two camps: formal and functional. For the former, transformational model is a target of discussion. In this line, the main task of a formal approach is to identify the topic in terms of structural operation including syntactic and morphological characteristics. For the latter, the approach is more interested in the pragmatic and discourse functions of the topic entity than just in its relations to syntactic structure.
2. A Brief Historical Review
3. Form or Function
3.1 From a formal perspective
3.2 From a functional perspective