Communication Today Reviews Custodians of the Internet: Platforms, Content Moderation, and the Hidden Decisions that Shape Social Media GILLESPIE, T.: Custodians of the Internet: Platforms, Content Moderation, and the Hidden Decisions that Shape Social Media. New Haven : Yale University Press, 2018. 296 p. ISBN 978-0-30017-313-0. Fatih Çömlekçi In June 2018, Tarleton Gillespie, a principal researcher at Microsoft Research New England and an affiliated Associate Professor at Cornell University (Department of Communication and Information Science), published a book titled Custodians of the Internet: Platforms, Content Moderation, and the Hidden Decisions that Shape Social Media. The book was published by Yale University Press and the author is well known thanks to his extensive works on the social impacts of new communication technologies and digital transformation of the media industry. Based on interviews with professional content moderators, creators and social media users, the book tries to explain how social media platforms moderate content and how they employ labour and technology into the process. It is self-evident that nowadays social media companies, professionals and algorithms decide what we see online and what we cannot reach. In this context, a vital question shows up as what their judgments are based on and how they decide to hide some of the content posted to the Internet? Social media platforms differ from the open Web in terms of moderating, recommending and curating the content. In this sense, the key claim of the book is that moderation is not an ancillary issue, but it is essential and constitutional to the functioning of social media platforms. However, content moderation procedures receive limited public attention even as it affects social relations, cultural production and the discourses which circulate within the society. Content moderation is generally defined as screening and evaluation processing of the user-generated content posted to websites, social networking sites and other digital platforms. This mechanism is ideally structured to facilitate cooperation with users and prevent online abuse. Some digital communities rely on volunteer moderation performed by their users while commercial content moderation of social media companies is done by subcontractors and employees to make profit. In his book, Gillespie focuses on commercial content moderation in terms of social media platforms such as Google, Twitter , Facebook, etc. and sheds light on controversial issues as decision-making by employees, usage of technology and transparency concerns. In addition to that, the author opens up rarely discussed subjects such as poor working conditions of moderators (most of them are freelancers) and psychological effects of being exposed to a gigantic amount of gruesome content. On 25 th May 2017, Olive Solon published an exclusive news story for The Guardian titled Underpaid and Overburdened: The Life of a Facebook Moderator . 1 This story was based on leaked testimony given by Facebook content moderators, i.e. those people who work to keep beheadings and sexual abuse images off Facebook while coping with poor working conditions, ill payment and psychological damage caused by grisly content they are exposed to. As brought forward in the book, thanks to the mentioned news story, moderation practices were finally opened up to closer scrutiny. Social media platforms are considered as vital digital spaces for citizen participation where people exchange ideas, debate and discuss. Nevertheless, the rapid dissemination of fake news via social media, the accusations that Russian trolls intervened during the 2016 presidential election in the USA, the rampant individual harassment and terrorist recruiting online are all crucial and current problems that the Internet has 1 SOLON, O.: Underpaid and Overburdened: The Life of a Facebook Moderator. Published on 25 th May 2017. [online]. [2019- 02-20]. Available at: <https://www.theguardian.com/news/2017/may/25/facebook-moderator-underpaid-overburdened-extreme- content>.