This chapter examines how the invention of lasers brought a major shift in ranging technology by offering a powerful alternative to radar. It’s well known that radar’s ability to detect objects beyond the range of sight played a huge role during World War II. The arrival of lasers in 1960 provided an opportunity to replace radio waves with light, which can provide distance data with exceptional precision, accuracy, and speed for both objects on Earth and in space. This chapter aims to give readers a basic understanding of how a typical laser rangefinder works and explores some notable applications, including the captivating lunar laser ranging experiments of the early 1970s that accurately measured the distance to the Moon.