Online Social Networking platforms (OSNs) have become part of people’s everyday life and their usage covers the deep-rooted need for communication among humans. During recent years, as people are questioning more and more OSN service providers, a new generation of proposals, based on blockchain became very popular thanks to the ethics adopted by these platforms. Steemit is the most important blockchain-based social networking site, which integrates, as main novelty an economic layer to the social media service. Steemit is implemented on top of Steem which, as in other blockchains, awards miners of the blocks with cryptocurrency. Steem miners, called witnesses, are not chosen based on the solution of a mathematical problem, as in Proof of Work based systems, but must be voted by other users. In this work, we decide to study the witnesses on Steem and their contribution to the social platform Steemit, and their social impact. We performed a set of analyses to shred light concerning their behaviour and to understand how they are socially perceived by other users. Analyses show an important social impact but, at the same time, some of them have a negative social impact. Their discussion is polarized towards content concerning Steem, Steemit, witnesses, and other platforms hosted on Steem.

在线社交网络平台（OSN）已成为人们日常生活的一部分，其使用涵盖了人与人之间沟通的根深蒂固的需求。近年来，随着人们对越来越多的OSN服务提供商的质疑，由于这些平台采用的道德规范，基于区块链的新一代提案变得非常受欢迎。Steemit是最重要的基于区块链的社交网站，它将社交媒体服务的经济层面作为主要新颖之处进行了整合。Steemit是在Steem之上实现的，与其他区块链一样，Steem用加密货币奖励区块的矿工。Steem矿工（称为见证人）并不是像基于工作量证明的系统那样，是根据数学问题的解决方案来选择的，而必须由其他用户投票。在这项工作中，我们决定研究有关Steem的证人及其对社交平台Steemit的贡献及其社会影响。我们进行了一系列分析，以弄清他们的行为，并了解其他用户在社交上如何看待他们。分析显示了重要的社会影响，但同时，其中一些具有负面的社会影响。他们的讨论与Steem，Steemit，证人以及Steem上托管的其他平台有关的内容是两极化的。