This document is concerned with six industrial gases: argon (Ar), carbon dioxide (CO2), helium (He), hydrogen (H), nitrogen (N), and oxygen (O). Properties, uses, safe handling, distribution, mixtures and effects on arc characteristics and welds are presented for flux cored arc welding (FCAW), gas tungsten arc welding (GTAW), gas metal arc welding (GMAW), electrogas welding (EGW), plasma arc welding (PAW), plasma arc cutting (PAC), laser welding (LW) and laser cutting (LC). Gas purging, gas distribution and safety practices are also covered.