This chapter discusses the necessary components of second language acquisition, that is, input, interaction, and output. While all language learning theories support the importance of input (written and spoken), they diverge in ways which input is connected to second language acquisition. The chapter then examines some of the second language acquisition theories, such as the interaction hypothesis, the noticing hypothesis, the cognitive-interactionist approach, the output hypothesis, and sociocultural theory, all of which explains how interaction leads to second language acquisition. The chapter moves onto specific pedagogical frameworks that support interaction, including communicative language teaching and task-based language teaching. Finally, the chapter delves into the role that output plays by discussing its functions for second language acquisition.

The chapter outlines the interactionist approach to corrective feedback in second language (L2) acquisition. Input-providing and output-prompting feedback types are addressed, including their potential role in facilitating L2 development. Historical and contemporary interactionist research is overviewed, and suggestions are made for future work in this area. The chapter closes with pedagogical recommendations for the use of corrective feedback in L2 classrooms.