Since the early days of the Internet, translators have made use of various online platforms to collaborate, socialize and otherwise interact not only with each other, but also with other social agents, including clients, subject matter experts, and non-translators interested in the profession. These platforms have included electronic mailing lists such as listserves, which translators have used to discuss terminology questions and computer problems, and chat socially about non-translation topics (Plassard 2010); specialized social networking sites such as Proz or TranslatorsCafe, where translators bid on translation contracts, and share knowledge via discussion forums, collaborative glossaries, and client-ranking databases (McDonough 2007; Pym, Orrego-Carmona, and Torres-Simón 2016; Risku and Dickinson 2009); blogs, which translators use to enhance their status and to make translation more visible to those outside of the profession (Dam 2013); and mainstream social networking sites such as Facebook and Twitter, which can help translators share content such as status updates, photos and videos related to their professional activities (Desjardins 2017). This special issue aims to examine the social, collaborative nature of translation in online spheres under the theme of "online social translation", a term that, as we will discuss, builds upon the concept of "community translation" described by Minako O'Hagan (2011, 12). The articles in this special issue have varying aims and discuss translation in different online platforms and geographic regions, but they all explore how translation occurs in online environments and the inherent social nature of the interactions between the various agents involved in producing, disseminating andin some casesreceiving these translations. The "social" in online social translation We have drawn the modifier "social" from social media studies. As social media researcher Christian Fuchs (2007, 4) argues, information and communication technologies and society are mutually dependant, as humans in society design and use the technology that in turn "enables and constrains, human cognition, communication, and cooperation". Such mutual dependence can be seen in the definition of social media offered by Kaplan and Haenlein (2010, 61), who use the term to refer to internet-based