An inert gas does not go through chemical reactions under certain conditions, and therefore it is commonly used to shield processes or reactions. One of the most common examples is using argon when welding to prevent the metal from reacting with oxygen and making the weld weaker with oxidized metal pockets.
It is possible to make an inert gas react under certain conditions to form compounds. Careful planning is needed to select the proper inert gas for the job.
Inert gasses can be used to drive out oxygen and prevent explosive situations. Oil tankers use nitrogen gas to keep the crude oil and oxygen from reaching a flash point. Deep sea divers use helium as an inert gas to dilute their oxygen.
Iron Noder 2017