Molecular processes remain hidden with imaging techniques approved for use in humans. Imaging in animals is required to understand the biological mechanisms in health and disease. Here, I will introduce how mice can glow to reveal the secrets of their biology and the fascinating world of imaging reporters that create measurable biosignals. Fluorescence imaging, using special light-emitting molecules, allows us to see and understand cellular activities in incredible detail. It's like having a high-powered microscope that shows us how genes express, proteins move, and cells communicate in real time. Bioluminescence imaging, inspired by nature's glow-in-the-dark creatures like fireflies, uses enzymes that light up when they interact with specific substances. This method is perfect for watching how diseases progress and how treatments work over time, all without invasive procedures. We'll explore the latest advancements in these technologies, showcasing glowing mice that help scientists track complex biological processes. These innovations not only produce fascinating images, they are also crucial for the development of new diagnostics and therapies.