Bluesky is a new social network built upon the AT Protocol, a decentralized foundation for public social media. It was launched in private beta in February 2023, and has grown to over 3 million registered users in the following year. In this paper we introduce the architecture of Bluesky and the AT Protocol, which is inspired by the web itself, but modernized to include streams of real-time updates and cryptographic authentication. We explain how the technical design of Bluesky is informed by our goals: to enable decentralization by having multiple interoperable providers for every part of the system; to make it easy for users to switch providers; to give users agency over the content they see; and to provide a simple user experience that does not burden users with complexity arising from the system's decentralized nature. The system's openness allows anybody to contribute to content moderation and community management, and we invite the research community to use Bluesky as a dataset and testing ground for new approaches in social media moderation.

翻译：蓝空是一个基于AT协议构建的新型社交网络，AT协议为公共社交媒体提供了去中心化基础。该平台于2023年2月启动内测，并在随后一年内发展到超过300万注册用户。本文介绍蓝空及AT协议的架构设计——该架构受万维网启发，但经过现代化改造，融合了实时更新流与加密认证机制。我们阐释蓝空技术设计如何服务于以下目标：通过系统各环节支持多个可互操作服务商实现去中心化；使用户能便捷切换服务商；赋予用户对所见内容的主导权；提供简洁的用户体验，避免因系统去中心化特性带来的复杂性困扰用户。系统的开放性允许任何人参与内容审核与社区治理，我们诚邀研究界将蓝空作为数据集和试验场，探索社交媒体审核的新方法。