This article gives an overview of the foundations in the areas of Information Search, Information Visualization and Information Processing. They form the basis for developing the model in the previous article (Hienert 2014). The field of Information Search provides various models which describe how users search for information. Several characteristics and methods are presented which are part of the search process. A major challenge is the heterogenous information basis on the Web. The section Information Visualization describes the goals, benefits, processes, models and techniques of interactive visualizations. It can be shown that interactive visualizations are beneficial for the representation of large and complex information collections. The following section Information Processing shows how users process information. For this purpose, basic mechanisms of cognitive processing and properties are presented. Based on this, the process of cognitive processing of visualizations is described. Interactive Visualizations can expand the cognitiv process in which an ongoing exchange between external and internal representation takes place. This article is a shortened and revised summary of the chapter in the dissertation of Hienert (2013).