Neon is a noble gas…
The noble gases are the elements in group 8 (also sometimes Group 0 IUPAC Style, or Group 18) of the periodic table. It is also called helium family or neon family. Chemically, they are very stable due to having the maximum number of valence electrons their outer shell can hold...
There are 6 noble gasses - Helium(2), Neon(10), Argon(18), Krypton(36), Xenon(54), Radon(86). A 7th was proclaimed on october 9th 2006. But it has a half time of .89 ms and can barely be called a thing. It has been proclaimed already in 1999, but the discovery was retracted for unknown reasons.
A neon lamp shines by letting a small current pas through a tube filled with noble gas at low pressure(different gas, different color). The first neon lights where showed at the 1893 worlds fair, and to the public in 1910. The first commercial sign was sold to a Paris barber in 1912. Neon is the most commonly used, then Argon, helium, krypton and xenon.

Neon has made a comeback recently with young artists all over the world proclaiming its use and detaching it from the heritage of Bruce Nauman. Today it is a medium like any other and most artist today use it as such. Danish artist Kasper Sonne and Jeppe Hein both use neon along with an aray of other mediums.

Jeppe Hein, Double Neon, 2006. Courtesy: Johan König, Berlin Photo: Holger Hübsch

Kasper Sonne, The Point of Being Pointless, 2006. Photo: The Artist
At Peres Projects Dan Attoe and Terence Koh both use neon in very different ways. Here is what Javier had to say about it
…but I am not per se a fan of any one medium, including neon, but at the same time i love it…what’s not to love, it is bright, but can be shut off and made dark…by in large there are few conservations issues, if it breaks, replace it, of course so long as the technology remains the same, or at least if it does not, that the artist stipulate that a new tech can be used to replace the older one…know what i mean…and the best best thing is it reminds me of shit like vegas, and billboards, strip joints, all the things that make life worth living, except for heroin of course, which is nasty even when it is good, but god lives in even those things that are good/bad, like neons, and me, and us, well, see you in a bit for the berlin weekend, word, jp