A 500-year-old placeholder
The canonical "Lorem ipsum dolor sit amet…" is a scrambled excerpt of Cicero's De finibus bonorum et malorum (45 BC), discovered to have been used by an unknown printer in the 1500s to make a type specimen book. It survived because it has the same letter distribution and rhythm as English-language Latin, which is a good stand-in for any Western text — but it lacks recognisable English words, so it doesn't distract from layout review.