The accurate measurements of surface topography are becoming important to many applications in both engineering and science. Optical interferometry is considered a preferable technique for featuring accurate 3D surface profiling since it is non-contacting, non-destructive and highly accurate. In combination with computers and other electronic devices, optical interferometry has become faster, more reliable, more convenient and more robust. There is now a wealth of new optical interferometry techniques on the market, or being developed in academia, that can measure surface topography with high precision. Each method has both its strong points and its limitations. This book explains in detail the basics of optical interferometry, their common language, generic features and limitations, and their simulation and uncertainties. Moreover, it provides an introduction to new frontiers in optical interferometry, including terahertz technology and optical frequency combs.