A social networking system includes a mechanism for incorporating nodes in the social graph, where the nodes are associated with a web page. Each web page includes one or more tags, which contain meta-information for defining the node in the social networking system, such as the type of the node. The social networking system retrieves the tags from the markup language document and stores their information in connection with the node for the web page. The web page may be outside of the social networking system's domain and may be operated by an entity other than the social networking operator; thus, third parties can define, create, and maintain nodes that are then used by the social networking system. Users may then interact with the nodes on websites outside of the social networking system, and these interactions are tracked by and reflected back within the social networking system.