Visualization leverages research on human visual perception. Its application in software engineering allows us to process information much quicker than in solely textual form. In this talk I will explain which laws for visually encoding/decoding information exist and how they are utilized by existing software visualizations to display different aspects of a software system. Then I will show how we applied this research to interactive source code navigation within Sourcetrail, a source explorer built on top of the LLVM/Clang LibTooling and Eclipse JDT Core libraries. The aim of this talk is to provide an overview of existing software visualization approaches and demonstrate their benefits and limits in day-to-day software development.