Backchannel is the practice of using networked computers to maintain a real-time online conversation alongside the primary group activity or live spoken remarks. The term was coined in the field of Linguistics to describe listeners' behaviours during verbal communication, Victor Yngve 1970.
The term "backchannel" generally refers to online conversation about the topic or the speaker. Occasionally backchannel provides audience members a chance to fact-check the presentation.
First growing in popularity at technology conferences, backchannel is increasingly a factor in education where WiFi connections and laptop computers allow students to use ordinary chat like IRC or AIM to actively communicate during class. More recently, researchers from Penn State University have explored bringing "backchannel" up front in classrooms - "ClassCommons, " to increase students' participation and promote community building in classrooms.
Twitter is also widely used today by audiences to create backchannels at technology conferences. When audience members add an event hashtag to their tweets (for example, #w2e was the hashtag used for the Web 2.0 Expo New York in 2009), anyone can run a Twitter search to review all the backchannel tweets related to that event.
Victor Yngve first used the phrase "back channel" in 1970 in the following passage: "In fact, both the person who has the turn and his partner are simultaneously engaged in both speaking and listening. This is because of the existence of what I call the back channel, over which the person who has the turn receives short messages such as 'yes' and 'uh-huh' without relinquishing the turn."
The first famous instance of backchannel communications influencing a talk occurred on March 26, 2002, at the PC Forum conference, when Qwest CEO Joe Nacchio famously lamented the difficulties of raising capital. Journalists Dan Gillmor and Doc Searls posted accounts, from the audience, in real-time, to their weblogs. Buzz Bruggeman, a reader of Gillmor's, emailed information about a recent sizable transaction that had made Nacchio very wealthy; both Gillmor and Searls updated their weblogs with that information.
In her article referring to the "Parallel Channel," PC Forum host Esther Dyson wrote, "around that point, the audience turned hostile." Many commentators later attributed the audience's hostility to the information people shared while surfing and communicating on their laptops during Nacchio's remarks.
Cliff Atkinson's book The Backchannel: How Audiences are Using Twitter and Social Media and Changing Presentations Forever explores the impact of the backchannel on live presentations, and describes practical steps that presenters can take to engage the changes.
Use in education 
Since its inception in 1998 at Argonne National Laboratory, the Internet2 initiative known as the Access Grid (a large-format presentation, video conferencing and interactive environment) has used backchannel communications to permit the node operators to pass URLs for display at another site, troubleshoot problems and even discuss what's for lunch at their location. The Access Grid backchannel has evolved from the use of a MOO to XMPP.
In 2009 Purdue University developed a tool called Hotseat that enabled students to comment on the course lectures in near real-time using open social networking tools such as Facebook and Twitter.
Using a backchannel for educational purposes can function as a formal class activity or even an independent discussion without instructor participation and awareness. Aside from the normal discussion, a backchannel can also be used for note taking, asking questions, offering suggestions on different topics, and sharing resources with other students and faculty members. There are many different media networks out there that can be used as a backchannel. Including Twitter, Facebook, Yammer, Instant Messaging and Google Moderator.
Backchannel is very much a discipline-in-progress. While many lament the diverted attention spans of people on chat, a number of people believe that backchannel can provide a valuable collaborative learning environment. Towards that end, a number of people are conducting their own backchannel experiments.
Joichi Ito's HeckleBot includes an LED text panel displays phrases sent from the chat room to catch the attention of the speaker or audience. The USC Interactive Media Division has experimented with "Google Jockeys" to feed visual information and search results between the speakers and the backchannel, projected on multiple screens surrounding their seminars. Software like SubEthaEdit allows for more formal backchannel: collaborative notetaking. In 2007 the Building Learning Communities Conference in Boston, Massachusetts used tools such as Twitter and Skype to create backchannels that included participants who were not on location and at times in remote parts of the world. At times presenters were not aware of the backchannel and other occasions the presenters themselves were involved in the backchannel.
In Amsterdam, Slandr.net's BackChannels provides backchannels amongst others at the local Mobile Monday events on a regular basis. Combining backchannels with live videostreaming by means of using services such as Ustream or Qik, people at home can join the discussion at the event virtually. The backchannels get their input from Jaiku, Twitter and SMS. A typical backchannel can display the chat transcript, inline pictures and voting. Experiments in Twitter subtitling have also been conducted combining recorded videostreams with the backchannel transcript.
- Yngve, Victor. "On getting a word in edgewise," page 568. Papers from the Sixth Regional Meeting [of the] Chicago Linguistic Society, 1970.
- Atkinson, Cliff. The Backchannel: How Audiences are Using Twitter and Social Media and Changing Presentations Forever, New Riders, 2009.
- The companion website to The Backchannel book by Cliff Atkinson
- Learning From (and About) the Backchannel
- Backchannel Modes
- Confessions of a Backchannel Queen - Liz Lawley's backchannel manifesto
- Bridging Diverse Groups - danah boyd's backchannel considerations
- Audience Gone Wild
- Sample of a backchannel chat
- BackChannels in The Netherlands, Europe
- Inviting Coworkers: Linking Scholars of Atlantic Canada on the Twitter Backchannel by Katherine O'Flaherty and Robert Gee, Acadiensis, vol. 41 no 2 (Summer/Fall 2012)
- What Is a BackChannel?