Collaborative Browsing is a new and promising research area whose purpose is to provide new collaboration schemes among users browsing the Web. To become an efficient collaboration tool, Collaborative Browsing should go far beyond a simple mechanism for coordinating the browsing of Web pages (like Web tours) and should include, in a integrated framework, awareness and communication facilities. A general functional architecture of a Collaborative Browsing system is presented in the paper. It relies on a rule-based system that permits to precisely express the browsing and communication strategies among users of a collaborative session. The proposed architecture is therefore general-purpose. By defining the policy rules specifying the behavior of a collaborative session, it may be easily adapted to specific applications in the eLearning or e-Business domains. The general architecture of CoLab, a Java-based software environment implementing the proposed Collaborative Browsing system is in...