Social media systems are as varied as they are pervasive. They have been almost universally adopted for a broad range of purposes including work, entertainment, activism, and decision making. As a result, they have also diversified, with many distinct designs differing in content type, organization, delivery mechanism, access control, and many other dimensions. In this work, we aim to characterize and then distill a concise design space of social media systems that can help us understand similarities and differences, recognize potential consequences of design choice, and identify spaces for innovation. Our model, which we call Form-From, characterizes social media based on (1) the form of the content, either threaded or flat, and (2) from where or from whom one might receive content, ranging from spaces to networks to the commons. We derive Form-From inductively from a larger set of 62 dimensions organized into 10 categories. To demonstrate the utility of our model, we trace the history of social media systems as they traverse the Form-From space over time, and we identify common design patterns within cells of the model.

翻译：社交媒体系统既多样又无处不在，已被广泛应用于工作、娱乐、行动主义及决策等诸多领域。由此，这些系统也呈现出多元化特征，不同设计在内容类型、组织方式、传播机制、访问控制等多个维度上存在显著差异。本研究旨在刻画并提炼一个简洁的社交媒体系统设计空间，以帮助我们理解各系统间的异同、识别设计选择可能带来的影响，并发现创新空间。我们提出名为"Form-From"的模型，该模型基于两维度对社交媒体进行表征：（1）内容形式，分为线程式（threaded）或扁平式（flat）；（2）内容来源，涵盖空间（spaces）、网络（networks）和公共池（commons）。我们通过归纳法从涵盖10类62个维度的更大维度集中推导出Form-From模型。为展示该模型的实用性，我们追溯了社交媒体系统随时间在Form-From空间中的演变轨迹，并识别了模型各单元格内常见的设计模式。