The AWS definition for a welding process is "a materials joining process which produces coalescence of material by heating them to suitable temperature with or without the application of pressure or by the application of pressure alone and with o without the use of filler material".

AWS has grouped the processes together according to the "mode of energy transfer" as the primary consideration. A secondary factor is the "influence of capillary attraction in effecting distribution of filler metal" in the joint. Capillary attraction distinguishes the welding processes grouped under "Brazing" and "Soldering" from "Arc Welding", "Gas Welding", "Resistance Welding", "Solid State Welding", and "Other Processes."

This table shows the official groupings and also shows the letter designation for each process. The letter designation assigned to the process can be used for identification on drawings, tables, etc.