This is a great start, @DKinzler (WMF)! I've made a few minor edits and typo fixes. I really like that you've integrated the page with Manual:Architectural modules/Cache. For the structure, I wonder if we can borrow from Manual:Object cache. I think a terminology section (canonical, stale) might be helpful and potentially a good place to define invalidation, expiry, and eviction.
Topic on Manual talk:Parser cache
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