This document provides an introduction to hydraulic components and systems. It describes common applications of hydraulics in machinery and discusses the advantages of hydraulic systems over other types of power transmission. The key components of hydraulic systems are identified as pumps, valves, actuators, hoses, and hydraulic oil. Examples of different types of pumps, valves, cylinders, and motors are illustrated and their basic functions and designs are explained. An educational electro-hydraulic positioning system is presented as an example application.