This entry provides a brief overview of research which has been conducted using a conversation analysis (CA) approach to understand computer-mediated interactions (henceforth CMIs). An increasing number of researchers use CA to investigate CMIs, because this methodology engages in systematic analysis of talk in everyday naturally occurring situations of social and institutional interaction. CA's central concern with interaction between human beings has provided researchers with a robust methodological foundation, based on previous work on phone and face-to-face conversation, to investigate new and unique forms of interaction in online settings, where participants are using either their first, additional, or a foreign language (L1 or L2). As the everyday use of communication technologies became more widespread in the 1990s, an increasing number of scholars began to explore CMI from a CA perspective (CA-CMI) in social settings, and soon after in institutional settings, especially educational.While users innovatively adapt to new online environments, technological resources and artifacts such as computers and communication software inevitably modify interaction, depending on constraints and affordances of the medium. For example, users invented emoticons as an attempt to replace the missing nonverbal dimension of online text interactions. CA researchers have therefore identified a range of technological-interactional configurations which are unique to CMI, and which shape interaction processes. These configurations include:1. one-to-one, multiparty (large group; small group; one to many) interaction; 2. text, voice, video interaction (used separately or in combination); 3. lack of access to interlocutors' messages-in-progress, except in voice, video and some text chat (see Anderson, Beard, & Walther, 2010); 4. asynchronousness, quasi-synchronousness or synchronousness of interactions, depending on degree of delay in writing, posting, or speaking contributions; 5. permanency and reviewability of text chat interaction compared with rapid fade of voice and video chat; 6. background noise, loss of channel, and other technical distortions, interruptions, and delays, including delayed and/or distorted transmission of interlocutors' image in video chat; 7. access to digital resources as an integral component of interaction (e.g., emoticons, hyperlinks to photos and films, interaction tools such as raise hand button to manage speakership in voice and video conversation); 8. copresence (in the same physical space) or geographical dispersedness of users; 9. video-game players' simultaneous attention to both interaction with the game and interpersonal interaction (see Piirainen-Marsh & Tainio, 2009).This range of technological-interactional resources and configurations which are part of the external context shape interaction in various ways, but need to be invoked by usersThe Encyclopedia of Applied Linguistics, Edited by Carol A. Chapelle.