ect or site; rather, technology is needed to allow user communities to construct, share, and adapt social machines so successful models evolve through trial, use, and refinement.

A number of research challenges and questions must be resolved before a new generation of interacting social machines can be created and evolved this way:

˲ What are the fundamental theoretical properties of social machines, and what kinds of algorithms are needed to create them?;

˲What underlying architectural principles are needed to guide the design and efficient engineering of new Web infrastructure components for this social software?;

˲How can we extend the current Web infrastructure to provide mechanisms that make the social properties of information-sharing explicit and guarantee that the use of this information conforms to relevant social-policy expectations?; and

˲How do cultural differences affect the development and use of social mechanisms on the Web? As the Web is indeed worldwide, the properties desired by one culture may be seen as counterproductive by others. Can Web infrastructure help bridge cultural divides and/or increase cross-cultural understanding?

In addition, a crucial aspect of human interaction with information is our ability to represent and reason over such attributes as trustworthiness, reliability, and tacit expectations about the use of information, as well as about privacy, copyright, and other legal rules. While some of this information is available on the Web today, we lack structures for formally representing and computing over them. Traditional cryptographic security research and well-known access-control-policy frameworks have failed to meet these challenges in today’s online environment and are thus insufficient as a foundation for the social machines of the future. Recent work on formal models for privacy^b has demonstrated that traditional cryptographic approaches to privacy protection can fail in open Web environments. Similar problems with copyright enforcement have also hampered the flow of commercial and scholarly information on the

the Web is changing
at a rate that may
be greater than
even the most
knowledgeable
researcher’s ability
to observe it.

Web. ²⁷ To this end, an exemplar Web science research area we are pursuing involves interdisciplinary research toward augmenting Web architecture with technical and social conventions that increase individual accountability to social and legal rules governing information use. ³¹ Continued failure to develop scalable models for handling policy will impede the ability of the Web to be the best possible medium for exchanging cultural, scientific, and political information.

Further, we can see from the dramatic growth of new collaborative styles of creating and publishing information on the Web that many of the social institutions we rely on to judge trustworthiness and veracity are missing from our online information life. Being able to engineer the Web of the future requires not only understanding it as a computational structure but also how it interacts with and supports interaction among its users.

An important aspect of research exploring the influence of the Web on society involves online societies using Web infrastructure to support dynamic human interaction. This work—seen in trout.cpsr.org and other such efforts—explores how the Web can encourage more human engagement in the political sphere. Combining it with the emerging study of the Web and the coevolution of technology and social needs is an important focus of designing the future Web. ³⁰

the Web of Data

This emerging area of study involves the heavy use of tagging provided by many of what are known as Web 2.0 technologies. Articles, blogs, photos, videos, and all manner of other Web resources may be annotated with user-generated keywords, or tags, that can later be used for searching or browsing these resources. Much has been made of how “folksonomies,” or taxonomies that emerge through the use of tags, can be used as metadata to help explain the content of the objects being described.

One aspect of tagging generating interest today is the need for “social context” in tagging. ²⁶ Many tags involve terms that are extremely ambiguous in a general context. For example, first names are popular tags on Flickr,