If you find, as I do, the act of physically marking books indescribably (in the literal sense) disrespectful (to the physical book), you probably felt great the first time you realised that PDFs could be digitally annotated. Equally so when Amazon’s Kindle brought eBooks into the mainstream. Unfortunately the story of highlights on Kindle has been one of some frustration and disappointment for me, in large part due to the restrictions placed on liberating highlights from the Amazon ecosystem, and the UX of highlighting on an e-ink Kindle, which remains to this today clunky, slow and always just a little too imprecise.