# Library Manager

The library is primarily composed of two data structures: **Asset** and **Entity**. Their relationship is illustrated in the following diagram:

<figure><img src="https://886210201-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FfI79StJ3o7OKZxf9vHhb%2Fuploads%2FLkfsBWWYy9AM51QeYmam%2FDataStructure.png?alt=media&#x26;token=225ba472-0e9a-42b0-9c1d-6f3a6c134498" alt=""><figcaption></figcaption></figure>

## Asset

Asset is a [ScriptableObject](https://docs.unity3d.com/Manual/class-ScriptableObject.html) that contains a collection of Entities. You can group commonly used sounds together in the same Asset. As you can see in the diagram above, all sounds related to the "Player" are stored within the Player Asset.

## **Entity**

An Entity represents a single sound, so when it is played, only one AudioClip from its [ClipList](https://man572142s-organization.gitbook.io/broaudio/core-features/design-the-sound#clip-list) will be played. Here, we set which AudioClip it should play, how it should be played, and what kind of characteristic it will have during playback.

### SoundID

When an entity is created in the LibraryManager, a SoundID is automatically generated. Once the SoundID is serialized (by \[SerializedField] or public), a dropdown menu appears in the inspector.

[see how to do this in action](https://man572142s-organization.gitbook.io/broaudio/overview/getting-started#declare-an-audioid-and-use-broaudio.play-to-play-it)