> For the complete documentation index, see [llms.txt](https://docs.roboflow.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.roboflow.com/datasets/manage-datasets/manage-classes.md).

# Set Dataset Classes

You can view, modify, and manage your annotation classes from the "Classes" tab on the project "Settings" page. These changes impact all images in your project (unlike some [preprocessing steps](/datasets/dataset-versions/image-preprocessing.md), which only impact a version). Take these actions when you are certain you want to make changes across all of your images.

Alphanumeric class names are recommended to maximize compatibility across computer vision tools. Roboflow does not support annotation classes with special characters aside from `-`.

## Renaming Classes

1. Open the "Classes" tab in your project "Settings" page.
2. Select the classes you want to rename using the checkbox column.
3. Click the "Rename" button that appears in the toolbar.
4. Enter the new name for each class. To merge classes, rename multiple classes to the same name.
5. Click "Review Changes" to see a summary of old and new names.
6. Click "Confirm Changes" to apply.

{% hint style="warning" %}
Renaming and merging are applied across all images in the project.
{% endhint %}

## Deleting Classes

1. Select the classes you want to remove using the checkbox column.
2. Click the "Delete" button in the toolbar.
3. Review the list of classes to be deleted and confirm.

{% hint style="danger" %}
Deleting a class removes all annotations of that class from every image in the project. This action is not reversible.
{% endhint %}

## Locking Classes

Toggle "Lock Classes" in the toolbar to prevent the creation of new classes. This is useful for ensuring annotators do not accidentally add new classes during the labeling process.

When Lock Classes is enabled, the "Find Objects with AI" button and the "Text Prompting" toolbar tool are hidden in the labeling editor, since both allow creating new classes via free-text input. The per-class "Prompt with SAM3" icon next to existing classes remains available.