There are two (or more?) types of Teflon. First TEFLON TFE = Tetrafluorethylene The unpolymerized Teflon looks like this:
F F | | C = C | | F F
Basically, Teflon is polymerized fluoridezed Ethene, polytetrafluoroethene (PTFE).
F F | | R - C - C - R | | F F
Teflon is also used as the trade name for a polymer with similar properties, perfluoroalkoxy polymer resin (PFA):
F F F F | | | | R - C - C - C - C - R | | | | F F F O | F - C - F | F
Teflon is the plastic with the lowest coefficient of friction. It is also used as a non-stick coating for pans and other cookware. Teflon is very unreactive, and so is often used in containers and pipework for reactive chemicals.
Teflon is the most common example given of a spin-off from the US Space industry with more down-to-earth applications.