Which company first implemented the item-to-item collaborative filtering algorithm that revolutionized product recommendations in e-commerce?

The world of retail has been transformed by personalization algorithms that tailor shopping experiences to individual consumers. These technological innovations have changed how we discover products and receive recommendations. Behind these powerful systems are brilliant minds and groundbreaking companies that pioneered different approaches. Test your knowledge about the early development of retail personalization technology that has now become ubiquitous in our shopping experiences.

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Amazon (developed by their engineers in the late 1990s)
Netflix (created for their original DVD rental service)
eBay (patented as 'Preference Engine Technology' in 2001)
Google (originally designed for their AdSense platform)