# ChainOfFact Core Concepts

## Event

An event is a single recorded fact. It represents something that occurred at a point in time.

Examples:
- A model produced an output
- A policy version was applied
- A decision was recorded

ChainOfFact does not interpret events.

## Append-Only Ledger

Events are written once and never modified or deleted.

Each event links cryptographically to the previous event.

## Absence

If a field or event was not recorded, it is considered UNKNOWN.

ChainOfFact does not infer missing information.

## Verification

Verification recomputes hashes from stored data and compares them to recorded values.

Verification does not require trusting ChainOfFact.

---

Canonical URL: https://chainoffact.com/docs/concepts