The amount of data that is being generated and collected as a by-product of contemporary business processes grows faster than the ability to process them. To a many, they are an excessive load, but there is much less those who, by means of specialized tools and methods, manage to analyze that data efficiently in order to improve their business results. This thesis illustrates the Interactive Visual Analysis as a way of presentation of large amounts of data, in order to reveal and understand the underlying information. Primarily, by means of proofing or disproving presumed thesis and revealing unexpected regularities. In order to familiarize the reader with the methodology, a short systematization of data and related terms is given. A general model of data is also presented; the way the data correlate mutually, different sets regarding their structure and role in the analysis. The term "visualization" has been explained and a brief description of the visualization history is given. Each phase of the process is described, together with the related terms and procedures, concluding with an overview of the most used chart types. By introducing interactivity, we enter the domain of Interactive Visual Analysis. The reader is introduced with basic techniques of achieving interactivity in visualization, and their application on different chart types. A few commercial software tools are listed, with the emphasis on ComVis – general purpose Interactive Visual Analysis tool,used in our example. The described methodology is depicted in details through an example on a real data set, gathered from POS terminals a hypermarket, in order to illustrate an approach to discover cognitions which may help in better understanding and improvement of the business activities.