What a hallucination really is
A "hallucination" is when an AI produces a claim that is fluent, plausible, and completely unsupported by any source. It isn't lying — it has no concept of true or false. A language model predicts the most likely next words, so it fills gaps with text that sounds correct rather than text that is correct.
That's why hallucinations are so hard to spot: there's no grammar mistake, no obvious tell. A fabricated statistic, an invented case citation, or a number that drifted by a decimal place reads with the same calm authority as a fact.