With the growing quantity of information around the world, besides the software development community, many other fields are interested in finding solutions for efficient information management. In this thesis, the problem of efficient information management is shown to be related to efficient user management. A dynamic user management system for web sites was developed. Though the problem may sound simple, the approach used to solve the problem shows the complexity of such task. Formal methods were used to specify the requirements of a Dynamic User Management System. The VDM specification language was chosen for this purpose. Validating the specification was done by executing the VDM-SL specification from the Java virtual machine; oracle testing was done based on the same approach. Finally a proposal was made for an implementation of the approach on an operating system. In the development of this module, a number of recently proposed technologies (like CORBA based visual validation..