If you followed Formula 1 in 2009 and 2010 you will probably recall the terms double diffuser and F-duct. However, unless you were in the aerodynamics department of an F1 team during that period you will probably only have a sketchy idea of how these devices actually produced the elusive, race-winning, downforce that is key to F1 success.
Brawn GP 2009 BGP001: Double diffuser carLicense: CC BY 2.0, Jose Ma Izquierdo Galiot