Understand LLMs · Lesson 04

Why can an LLM hallucinate?

Why can a linguistically convincing answer still be false or unsupported?

Level
Beginner
Core time
13 min
Updated
27 July 2026
Prerequisites
None
Progress
Not started

Start with the mechanism

Three steps to keep in mind

  1. 1

    Split the answer into claims

    A polished paragraph may contain several independently checkable statements.

  2. 2

    Find suitable evidence

    Prefer primary, current, accessible sources that directly address each claim.

  3. 3

    Classify support

    Evidence can support, contradict, or remain insufficient for a conclusion.

Try it yourself

The lab isolates this mechanism with a small, transparent simulation. Everything runs locally in your browser.

Open “Check a claim

Keep these three ideas

Go deeper when you need it

Technical detailWhat the short version leaves out

Retrieval and tools can ground an answer, but they can also retrieve irrelevant material or be interpreted incorrectly.

Useful systems expose uncertainty, separate facts from hypotheses, and make sources easy to inspect.

Your local progress

Status: Not started

Progress stays on this device.