What is Sulfur Hexafluoride?

What is Sulfur Hexafluoride? What's in it that brought it to the top 100 of ggole's most searched keyword? To answer these questions, here are the facts:

Sulfur hexafluoride (SF6) is an inorganic, colorless, odorless, non-toxic and non-flammable gas.

Uses:

Medical: SF6 is relatively slowly absorbed by the bloodstream, therefore it is used to provide a long-term tamponade or plug of a retinal hole in retinal detachment repair operations.

Tracer compound: Gaseous SF6 is an ongoing commonly used tracer gas for use in short-term experiments of ventilation efficiency in buildings and indoor enclosures, and for determining infiltration rates. Two major factors recommend its use: Its concentration can be measured with satisfactory accuracy at very low concentrations, and the Earth’s atmosphere has a negligible concentration of SF6.

Other uses:

Sulfur hexafluoride is also used as a reagent for creating thrust in a closed Rankine cycle propulsion system, reacting with solid lithium as used in the United States Navy’s Mark 50 torpedo.

SF6 plasma is also used in the semiconductor industry as an etchant.
The magnesium industry uses large amounts of SF6 as inert gas to fill casting forms.
Sulfur Hexafluoride is also used to pressurize the waveguide in radar systems.