Which technological advancement first made 'window shopping' possible in the 1830s?

The retail experience has evolved dramatically over centuries, but some innovations have fundamentally changed how consumers interact with products. In the 19th century, one revolutionary concept transformed retail marketing by allowing potential customers to browse merchandise without entering a store. This innovation created a new form of consumer engagement and set the foundation for modern visual merchandising techniques that retailers still employ today.

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Plate glass manufacturing process that allowed for large, clear display windows
Electric lighting that illuminated store displays after sunset
Mannequins that could realistically display clothing and accessories
Movable type printing that enabled widespread advertisement of products