The aim of this paper is to investigate the functions of discourse markers mainly in conversation. In Chapter 1, I will discuss what is a discourse. In Chapter 2, I will focus on the textuality of a discourse. In Chapter 4, I will give general views of discourse markers. In Chapter 5, I will illustrate the use of discourse markers in written texts. Chapter 6 deals with a variety of conversational structures. In Chapter 7, I will explore the functions of discourse markers in conversation.