Metadiscourse is defined as discourse about the ongoing discourse. Metadiscourse is widely seen as the linguistic manifestations of writers and speakers taking the audience and their perceived needs into consideration when creating discourse and designing messages. Since applied linguistics research into metadiscourse took off in the 1980s, at least two different strands have developed: the interactive approach and the reflexive approach. The key distinction lies in whether what is seen as central for metadiscourse is the interaction between the writer and the reader, as in the interactive approach, or the reflexivity involved in the awareness of discourse as discourse, as in the reflexive approach. The distinction has effects on the definition, which is considerably more inclusive in the interactive approach, where phenomena such as stance and hedging are seen as inherently part of the category of metadiscourse. This entry will offer a description of the two main research strands, along with a brief overview of the historical development of metadiscourse research. An overview of methodologies used will also be given, including selected variables that have been found to affect the use of metadiscourse. The entry will close with a few remarks on new developments in the area.