Reflection imaging, with either radar or seismic waves, is a powerful tool for probing the earth’s subsurface. However, the data we record in the field gives a distorted picture and accurate imaging requires that we focus the data. To focus the data, we utilize a broad class of methodologies collectively referred to as migration. Because of gains in computational power, the last ten years has seen a particular method known as reverse-time migration become the preferred approach to migration. It is preferred because it utilizes the full wave equation and therefore requires no approximation in the solution. Through pictures and movies, I will demonstrate how reverse-time migration works and show why it is such a powerful imaging tool.