This tutorial is intended to provide an understanding of the fundamental principles of positive displacement reciprocating pumps of both power and direct active types. Topics include: 1. A definition and overview of the pump types - Including the differences between single acting and double acting pumps, how both types work, where they are used, and how they are applied. 2. Component options - covers aspects of valve designs and when they should be used; describes the various stuffing box designs available with specific reference to their function and application, and points out the differences between plungers and pistons and their selection criteria. 3. Specification criteria and methodology - What application information is needed by pump suppliers to correctly size and supply appropriate equipment? 4. Additional topics - Volumetric and mechanical efficiency, net positive suction head available and required, plus piping systems (suction and discharge) basic principles for reciprocating pumps, which are different for those of centrifugal machines.