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：社交媒体系统既普遍存在又形态各异。它们已被广泛用于工作、娱乐、社会活动与决策制定等多种用途。因此，这些系统也呈现出多样化趋势，在内容类型、组织方式、推送机制、访问控制及其他诸多维度上存在显著差异。本研究旨在对社交媒体系统进行特征刻画，进而提炼出一个简洁的设计空间，以帮助我们理解其异同、认识设计选择可能带来的后果，并识别创新空间。我们提出的模型名为"形式与来源"（Form-From），从以下两方面对社交媒体进行特征描述：（1）内容形式，分为线程式与扁平式；（2）用户获取内容的源头或对象，涵盖空间、网络与公共领域三个层级。该模型基于包含10个类别、62个维度的更大规模分析集，采用归纳法推导得出。为展示模型效用，我们追溯了社交媒体系统在"形式与来源"空间中随时间演化的历史轨迹，并识别出该模型各单元格内的常见设计模式。