It is scrambled Latin from Cicero's "De Finibus Bonorum et Malorum" (45 BC). The familiar passage begins mid-word — "dolorem ipsum" became "lorem ipsum" — because a typesetter cut it there in the 1500s. It survives because it has roughly the letter distribution and word length of English prose without being readable, so it does not distract from the design.
Should I use Lorem Ipsum in a design?
For pure layout and typography testing, yes. For anything a stakeholder will review, it is genuinely risky: nonsense text hides real problems such as headlines that are too long, empty states, and content that simply does not exist yet. Many teams now prefer realistic draft copy for exactly that reason.
Why does the output vary between runs?
Sentence length, word choice and comma placement are randomised so repeated generations do not produce visibly identical blocks — which would look wrong in a mockup with several paragraphs.