# Metamaster

A Metamaster, also known as an Uniform Resource Identifier (URI) Owner, is commonly used by creators to display NFT specific metadata. On creation, a collection can be passed a Metamaster - either a user address or the zero address.

#### If set to a **User Address**:

The user has the ability to change the metadata assigned to any NFT in that collection. 

This option could be very valuable for any collection owner that would want to ensure NFTs within their collection meet certain quality standards, or for NFT collections that require metadata updates after they have been minted. 

The Metamaster can be changed at any point - to learn more, read [Developer - Managing a Capsule Collection](/capsulenft/developer-walkthroughs/developer-managing-a-capsule-collection.md).

#### If set to the **Zero Address**:

The Metamaster can alternatively be set to the zero address in order to prevent anyone from changing NFT metadata in a collection. After setting the Metamaster to the zero address, the metadata and Metamaster can no longer be changed by any user.

{% hint style="info" %}
**Collection *****Metamaster***** vs. Collection *****Owner***

A Metamaster is the controller of all metadata in the Capsule Collection, meaning they have the ability to reassign tokenURI data. 

An Owner is able to lock any Capsule Collections they own. In addition, if a Capsule Collection is private, only the Owner is able to mint to that collection. 

A collection may have one of the following structures:

* User A is Metamaster and Owner.
* User A is Metamaster, and User B is Owner.
* The Metamaster is set to the zero address. User A is Owner.
  {% endhint %}

### Related Tutorials

{% content-ref url="/pages/6GI3x8AzCdRQjo6XPNYH" %}
[Developer - Managing a Capsule Collection](/capsulenft/developer-walkthroughs/developer-managing-a-capsule-collection.md)
{% endcontent-ref %}


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