# About Occurrences

> What occurrences are and how they work in Asset Transformer Studio

In Asset Transformer Studio, the Product Structure is composed of one node type only, called *occurrence*. The Product Structure is an *occurrence tree*.

An occurrence is the fundamental object of a scene's Product Structure, and is similar to the [GameObject concept in Unity](https://docs.unity3d.com/Manual/class-GameObject.html).

An occurrence is by default an empty node that does not contain any geometry. It does not accomplish much by itself, but it acts as a container for *components*, which implement the real aspect and/or functionality.

An occurrence is identified by a unique Id, and owns *properties* carrying information about the occurrence.

![Occurrence structure](/api/media?file=/asset-transformer-studio/2026.5.0/media/NewItem285.png)

See the following topics to learn more about occurrences:

* [Occurrence Id](/asset-transformer-studio/2026.5.0/manual/data-preparation-fundamentals/about-occurrences/occurrence-id.md)
* [Occurrence Types](/asset-transformer-studio/2026.5.0/manual/data-preparation-fundamentals/about-occurrences/occurrence-types.md)
* [Occurrence Properties](/asset-transformer-studio/2026.5.0/manual/data-preparation-fundamentals/about-occurrences/occurrence-properties.md)
* [Occurrence Components](/asset-transformer-studio/2026.5.0/manual/data-preparation-fundamentals/about-occurrences/occurrence-components.md)