# Category Schema (Ontologies)

A project’s category schema (also known as *ontology*) is the list of labeling tools available in the project.

Ango Hub allows project owners to set the project’s ontology directly from the *Category Schema* section of the *Settings* page.

<figure><img src="https://3895963154-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FTcOUG6rfWxqGM0N4db2P%2Fuploads%2FRn0U6LR28eZUide9gOof%2Fimage.png?alt=media&#x26;token=da9020ce-fb63-4b3d-8b7c-79b9c455d78c" alt=""><figcaption></figcaption></figure>

The ontology created from this section is then reflected in the left sidebar of the labeling editor:

![](https://3895963154-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FTcOUG6rfWxqGM0N4db2P%2Fuploads%2FFH9PGJO4sgkH3AkmNuJZ%2FScreen%20Shot%202021-12-17%20at%2014.16.29.png?alt=media\&token=d9cb5f28-77a1-4be1-96ea-013b25330aba)

## How to create a project ontology <a href="#how-to-create-a-project-ontology" id="how-to-create-a-project-ontology"></a>

From the project’s *Settings* tab, enter the *Label Set* section.

Click on the *Add Category* button and choose the labeling tool to add. Each tool has a slightly different setup process. [See here for a list of all labeling tools available in Ango Hub, and how to add them to your project.](https://docs.imerit.net/labeling/labeling-tools)

For a guide on how to create nested classifications, [see here](https://docs.imerit.net/labeling/labeling-tools/tools/nested-classifications).

## How to copy a project's ontology to a new project

Please [check this guide](https://docs.imerit.net/how-to/manage-projects/transfer-project-ontologies-between-projects).

## Browse and Restore Previous Ontology Versions

From the Settings tab, in the *Category Schema* section, click on the "History" icon on the top-right to open a history of all workflow versions in the current project.

{% hint style="info" %}
Category Schema history started being recorded on March 12, 2025. Versions before then had not been saved.
{% endhint %}

<figure><img src="https://3895963154-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FTcOUG6rfWxqGM0N4db2P%2Fuploads%2FwyxjEvBJZtzcj2PHFq9B%2Fimage.png?alt=media&#x26;token=73d3cf1d-7daa-46f9-97f9-d30e42df4e76" alt=""><figcaption></figcaption></figure>

To view a previous version of this project's ontology, click on *Preview*. To restore it, click on *Save* while the version you need is previewed.