# Learn

New to oracles? Start here. The HTML site lists eight short guides that take you from "what is an oracle?" to how REP keeps answers honest. No background needed.

Only one guide has been written so far. The other seven are placeholders on the HTML site and have no Markdown copy yet.

## Guides with a Markdown copy

- [How Augur answers a question](/learn/how-augur-answers-a-question.md): Ask, report, challenge, final answer: one example from start to finish. (Start here, guide 2 of 4, about 6 minutes. Review flag: this guide still needs review.)

## Placeholder guides (HTML site only)

- What is an oracle? (Start here, guide 1): why smart contracts need someone to tell them what happened, and why that someone matters.
- Disputes, bonds and forks (Start here, guide 3): why each challenge doubles the bond, and what happens at the last resort.
- What REP does (Start here, guide 4): how REP secures answers, and what holders can choose to do.
- Writing questions an oracle can answer (For builders): clear outcomes, a firm deadline and criteria that leave no room for doubt.
- When a question can't be answered (For builders): what "Invalid" means, and how to avoid it.
- Reading the Augur Lituus whitepaper (Research): a guided walk through the January 2026 paper, section by section.

## Key terms

The words you'll meet most often, in plain language.

- **Oracle.** A service that tells a blockchain what happened in the real world.
- **Report.** A proposed answer to a question, backed by a REP bond.
- **Challenge.** A different answer posted with a larger bond. It reopens the question.
- **Bond.** REP put at risk behind an answer. Wrong answers lose most of their bond to the winners.
- **Fork.** The last resort. REP holders move to the answer they believe; the total that moves decides the original oracle's answer.
- **REP.** Reputation: the token that secures Augur's oracle.
- **Universe.** A version of the ledger with its own REP. A fork creates one child universe per answer.
- **Invalid.** The result for a question that's malformed or can't be answered.