An inert gas is a gas that is generally non reactive with other substances. The term "inert" means non reactive. Gases are being chemically inert if their atoms don't combine with other atoms in chemical reactions. The most common inert gases are, helium (He), argon (Ar), neon (Ne), Krypton (Kr), xenon(Xe) and radon (Rn).
Uses: Helium is used in inflating aeroplane tyres. Neon is used in discharge tubes and fluorescent bulbs used for advertising process. Argon is used for filling electric bulbs. Xenon and Krypton are also used in light bulbs.