Linked from
The 9 pages that link to Polarizer, each with the reason it gives.
PolarizationRelated: It converts polarization differences into changes in transmitted intensity.
PolarimetryRelated: Rotating or combining polarizers reveals an incoming beam’s polarization.
DichroismRelated: Dichroic absorption is one physical mechanism used to make polarizers.
Malus' lawBroader topic: An ideal polarizer serves as the analyzer in the law.