But how does that work in practice? Does their system determine those signals or are they fed to it as input? How can it possibly provide a generic solution t

But how does that work in practice? Does their system determine those signals or are they fed to it as input? How can it possibly provide a generic solution to "personalizing a message" that works across all apps and is not just something trivial like the example in the interview? On the web the kinds of "personalization" I can think of are public account profiles, targeted advertisements, recommendation engines ("you may also like...", "products like this...", etc.), algorithmic newsfeeds and history-sensitive search. If their software does any of those, maybe they should just say what it does.