> ## Documentation Index
> Fetch the complete documentation index at: https://docs.attest.so/llms.txt
> Use this file to discover all available pages before exploring further.

# Attestations

> Core concept: what attestations are and how they work

## What is an Attestation?

A signed statement by an issuer about a subject, stored on-chain.

**Example**: "KYC Provider X attests that Wallet Y is verified at level Basic"

## Attestation Properties

| Property         | Description                    |
| ---------------- | ------------------------------ |
| `uid`            | Unique identifier (32 bytes)   |
| `schemaUid`      | Reference to schema structure  |
| `attester`       | Who created the attestation    |
| `subject`        | Who the attestation is about   |
| `value`          | Attestation data (JSON string) |
| `timestamp`      | When created                   |
| `expirationTime` | When it expires (optional)     |
| `revoked`        | Whether invalidated            |

## Lifecycle

```
Created ──▶ Active ──▶ Expired
                │
                └──▶ Revoked
```

**Created**: Attestation issued and stored on-chain

**Active**: Valid and queryable

**Expired**: Past expiration time (still on-chain)

**Revoked**: Explicitly invalidated by attester

## Use Cases

* **KYC/Identity**: Verify user identity
* **Credentials**: Professional certifications
* **Reputation**: On-chain reputation scores
* **Access Control**: Gate access to services
* **Compliance**: Regulatory attestations

## Schema Relationship

Every attestation references a schema that defines its structure:

```typescript theme={null}
// Schema defines structure
'struct KYC { bool verified; string level; }'

// Attestation follows structure
{ verified: true, level: 'basic' }
```

## Next Steps

<CardGroup cols={2}>
  <Card title="Schemas" icon="cube" href="/concepts/schemas">
    Learn about schema design
  </Card>

  <Card title="Delegates" icon="key" href="/concepts/delegates">
    Off-chain signing with BLS keys
  </Card>
</CardGroup>