This document classifies and provides examples of positive displacement machines and rotodynamic machines. Positive displacement machines include piston pumps and motors, sliding vane machines, scroll machines, screw machines, and Roots blowers. Rotodynamic machines include impulse turbines like the Pelton wheel, reaction turbines like the Francis and Kaplan, hydraulic couplings, windmills, centrifugal compressors, turbochargers, gas turbine engines, steam turbines, rocket engine turbopumps, and ship screws and aircraft propellers. Examples of specific machines that are described include the ancient shadouf water pump, Hero's turbine from 2000 years ago, and the Titanic.