Modern gun propulsion techniques are driven by the desire to increase muzzle kinetic energy as a means to enhance weapon lethality, reduce costs, increase reliability, and improve vulnerability. In recent years, a significant part of research and developmental activities has been focused not only on conventional solid‐propellant and novel liquid‐propellant gun propulsion techniques but also on advanced concepts, particularly those offering substantial performance increase. High performance can be achieved by pure electric systems(coil or rail gun) as well as by combining chemical propulsion either with gasdynamic principles (light gas gun or ram accelerator) or with electrothermal techniques (hybrid gun). Part I of this paper deals with the fundamentals of projectile acceleration techniques. The objective is to provide the basis for understanding gun technology and to lay the basis for assessing present and future developments.