The information visualization process can be described as a set of transformations applied to raw data to produce interactive graphical representations of information for end-users. A challenge in information visualization is to provide flexible and powerful ways of describing and controlling this process. Most work in this domain address the problem at either application level or toolkit level. Approaches at the toolkit level are devoted to developers while approaches at the application level are devoted to end-users. Our approach build on previous work but goes one step beyond by proposing a unifying view of this process that can be used by both developers and end-users. Our contribution is a system named STOOL with a three-fold contribution: (1) a style-sheets based language for the explicit description of the transformation process at stake in information visualization, (2) an application that automatically builds interactive and graphical visualization of data based on style-sheet descriptions, (3) a user interface devoted to the conception of style sheets. In this paper, we present STOOL basic concepts and mechanisms and provide a case study to illustrate the benefits of using STOOL for the interactive and visual exploration of information.