The Web is different from most hitherto-studied systems in that it is changing at a rate which is of the same order as, or maybe greater than, our ability to observe it. This introduces many new inter-disciplinary research challenges. How are we to instrument the Web and how can we log it or identify behaviours? Once we are able to measure what is happening in this world of constant flux, we can then turn to the issue of how to model and understand it. Mathematical tools help to analyse the changing structure of the Web (e.g., using graph theory). Sociology can develop an understanding of the two-way process by which individuals and technologies shape each other. A legal perspective is needed to assess whether law is a catalyst for Web dynamics, or merely reactive to it. Linguistics will allow us to assess how language (and e.g., the preponderance of people for whom English is a second language) is affecting the development of the Web. As the Web changes, so does practice. Understanding the dynamics and pace of change is very important in a number of industries.