What does "AI engines cite sources" mean in Perplexity and Gemini?

https://productive-breadfruit-0ea.notion.site/I-ve-been-tracking-how-models-represent-us-saving-screenshots-in-a-dated-folder-to-see-the-drift-M-38c44410a6a080e18ba5c61a40e28792

As of late 2023, the search industry shifted from ten blue links to a paradigm where the answer is often generated entirely within the interface