Neon
Neon and sometimes argon
Its mostly Argon and a small amount of mercury. Its the main ingredients inside a flourescent lightbulb, which are used to light up billboards and highway signs. See the related link for more information on flourescent bulbs.
Usually a gas, neon is also available as a pressurized liquid. Neon gas is used in red lights used as exit signs or illuminated advertising signs, TV picture tubes, lasers, and voltage testers. Liquid neon is used as a refrigerant in cryogenics.
A noble gas is inert. However they sometimes sodium ions or mercury vapor.
If you're referring to neon signs, the gas used is either neon, or argon (used with mercury). Fluorescent lights use the same principle as neon signs.
Neon
Neon
Neon gas is used in neon-signs, Vegas is full of them.
I't actually spelled Xenon and it's used in electric signs (some signs have Neon gas, others have Xenon)
Neon gas is a colorless odorless gas that fills tubes that are often used in electrical advertising signs.
That gas is neon
Neon