As software systems are continuously being developed and more and more programmers are working on a project, program comprehension is a topic that should be analyzed thoroughly to help the industry accommodate changes for engineers, regardless of experience or age. This way, we tackled the field of Software Visualization and analysed its characteristics in the recent literature through a Systematic Literature Review, where we investigated what and how software is visualized, and how such tools can be empirically validated. Our study notes a mass use of three different approaches for software visualization, while also discovering representations in both graphical and numerical forms. This study also gathers information and views on where software visualization can expand with the current use of artificial intelligence in the day-to-day processes of industry software engineering. Our research shows that current software visualization tools are mainly based on the same three topics, Code Metrics, Dependencies, and Code Changes, but are starting to expand in different directions, tackling more specific issues as the software development field is quickly growing, offering a development perspective towards new or combined approaches of how can program comprehension be enhanced.