We discuss here the recent developments on the Internet and their implications for high performance distributed computing. We outline the ongoing process of building a World-Wide Virtual Machine and we expose Java as the most promising candidate for Web based computing. We start with a brief review of the Java history (Chapter 2) and compare it with selected related VM approaches in the past such as NeXT, Telescript and MOVIE/HPFI (Chapter 3). We point out what worked, what didn't and why, and how did the Java phenomenon happen. Next, we summarize the current status of Java, including the current products and the ongoing developments (Chapter 4). We then discuss the implications of the Java technology for the HPCC community (Chapter 5), followed by the analysis of near term future projections towards 'all Java' systems (Chapter 6). This leads in a natural way to the distributed Java environments - we summarize the enabling technologies for Java multiserver systems, we present the concept of a world-wide virtual machine (Chapter 7), evolving from the current mix of Web technologies towards an 'all Java' system, and we illustrate our ideas in terms of NPAC technology prototypes (WebVM, WebFlow, Bridge Collaboratory) and selected applications (Visible Human, CareWeb).