This work provides an overview of common flow velocimetry and diagnostic techniques, including their working principles and the application of these techniques. Probe velocimetry techniques such as pitot tubes and hot wire anemometry are discussed along with unintrusive techniques such as Laser Doppler Velocimetry and Particle Image Velocimetry. Density, pressure, and temperature diagnostic methods are also examined, in particular shadowgraph/schlieren imaging, pressure/temperature sensitive paints, and infrared thermography. Benefits and drawbacks of each method are examined as well as the applications. The goal of this review is to provide the reader with a basic understanding of the methods discussed, as well as to give insight as to which methods are particularly useful and applicable to engineering measurements.