- The document discusses OpenSocial, an open-source platform that allows developers to build social applications and widgets that can run across different social networking platforms. - OpenSocial aims to address the problem of applications being locked into single social networks by providing a common way for applications to integrate social features and data across sites. - The document outlines the history and development of OpenSocial, how it works, and provides examples of how companies like Google, Atlassian, and others are using it to build social features into their products and platforms.