The authors propose a client-side agent for exploring and categorizing docu
ments on the World Wide Web. As the user browses the Web using a usual Web
browser, this agent is designed to aid the user by classifying the document
s the user finds most interesting into clusters. The agent carries out the
task completely automatically and autonomously with as little user interven
tion as the user desires. The principal novel components in this agent that
make it possible are a scalable hierarchical clustering algorithm and a ta
xonomic label generator. In this paper, the overall architecture of this ag
ent is described and the details of the algorithms within its key component
s are discussed.