Th3 Core

This seemingly cosmetic change may seem far from revolutionary, but has been built through careful and vigorous A/B testing; scaling APIs to Wikipedia levels of traffic and a change to how we build our code (blog post to follow). Our testing shows that the feature makes it easier and more efficient for Wikipedia readers to interact with our content and get more context about a topic on Wikipedia.
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The goal of page previews was to decrease the cost of exploration for each blue link you come across, allowing readers to satisfy their curiosity or clarify a confusing or unknown topic without the burden of opening a new page and navigating back to the original.
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And for three, the number of classical pageviews is slightly decreasing. That might seem like a strange thing to be happy about

Nearly ~28 percent of Wikipedia’s traffic comes from clicking on internal blue links. a.k.a going down the rabbit hole.
~2 million links get hovered per minute across all Wikipedias
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Add value not pain
Modifying such frequent behavior is difficult. We began by using qualitative and quantitative insights to conclude the interaction timeline for showing a preview.
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Given Wikipedia’s scale, a minor change in any of these variables could always result in a massive impact on the experiences of the end user as well as on our infrastructure