Uploaded January 2026 | Updated September 2026, 27 minutes ago

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Day 31/42: What Is Hallucination?

Yesterday, we talked about metrics.
Today, we look at the most dangerous failure.

Hallucination is when an LLM confidently makes things up.

Not because it’s lying.
Because it’s guessing the next token, not checking facts.

If the answer sounds plausible, the model keeps going.

This is why fake citations happen.
And why confident tone means nothing.

Missed Day 30? Start there.
Tomorrow, we talk about another weakness: math and logic failures.

I’m Louis-François, PhD dropout, now CTO & co-founder at Towards AI. Follow me for tomorrow’s no-BS AI roundup 🚀

#Hallucinations #LLM #AIExplained #short