This chapter specifically deals with the topic of data and presentation visualization. It elaborates in depth on how human perception works. Preattentive features, relevant Gestalt principles, and principles for good design are introduced. Subsequently, advice and tips for designing both slides and data graphs and diagrams are given. The author explains current and future conventions of data visualizations and also discusses forms of data manipulations. The latter must be avoided at all costs to maintain the trust of the audience. The chapter concludes with a discussion about a manipulative graph, which the readers are supposed to analyze based on what they have learned previously.