# Schema

## What is Verifiable Credential Schema or Data Models?

As per the [Verifiable Credentials JSON Schema 2022](https://w3c-ccg.github.io/vc-json-schemas/#verifiable_credentials_data_model) specification:

> The Credential Schema is a document that is used to guarantee the structure, and by extension the semantics, of the set of claims comprising a [Verifiable Credential](/hypersign-identity-network/developers/hid-ssi-sdk/hypersign-schema-sdk.md). A shared Credential Schema allows all parties to reference data in a *"known way"*.

A schema can be viewed from four perspectives: the author, issuer, verifier and holder.

* **Author**: An author creates a schema and registers it in Hypersign blockchain as to provide a blueprint for a *Verifiable Credential*, specifying the shape and format of the data in such a credential.
* **Issuer**: Issuers utilize schemas to provide structure and meaning to the data they issue as *Verifiable Credentials*. By using schemas, issuers contribute to a credentialing ecosystem that promotes the usage and adoption of data standards.
* **Verifier**: Verifiers processes a *Verifiable Credentials* and need to do so with knowledge of the terms and data the compromise the credentials. Credential Schemas aid a verifier in both requesting and processing credenetials that have been produced in a well-known format.
* **Holder**: Holders, or those who are the subject of credential issuance, can make sense of the data they control by evaluating it against a data schema. When data is requested from a holder which references a Credential Schema the holder has the capability to to present the data specifically requested by the verifier.

Note: Often, Issuer and Author of schema may be same.


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.hypersign.id/core-concepts/schema.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.