# Share properties across multiple 2D Physics Core components

> Create a definition object to configure properties such as gravity, friction, position, and shape.

> **Note:**
>
> This documentation is about using Pose, Area, and Constraint components. To use 2D physics in the Unity Editor using components like the Rigidbody 2D component, refer to [2D physics](/engine/6000.7/manual/unity2d/2d-physics.md.md) instead.

To share properties across multiple physics objects, use the following:

* A definition asset to share a set of component properties, such as gravity or friction.
* A geometry asset to share a shape.

Definition assets and geometry assets are files in the **Project** window that store the shared values.

## Share a set of area properties

Follow these steps:

1. Right-click in the **Project** window and select **Create** > **2D** > **Physics (Core)**.

2. Select the category and definition type you want to create. For example, select **Area** > **Area Definition** to create a shared set of properties for any Physics Area component.

   > **Note:**
   >
   > Physics Area components all use the same Area Definition asset type, but each Physics Constraint has its own definition asset type. For the full list, refer to [Connecting 2D Physics Core objects](/engine/6000.7/manual/unity2d/2d-physics-api/connect-objects.md).

3. Select the asset Unity creates in the **Project** window, then adjust its properties in the Editor window.

4. In the **Inspector** window of any 2D Physics Core component that matches the definition type, drag the definition asset into the **Definition Asset** property, or select the picker (**⊙**).

To stop a component using a shared definition asset and revert it to using its own local properties, select **Make Local**.

> **Note:**
>
> For Area components, you can also create a Physics Contact Filter asset to share a different set of contact properties, and a Physics Surface Material asset to share a different set of surface properties. If you provide these assets, they override the same properties in the definition asset.

## Share a shape

To share a shape across multiple Area components, create a shared geometry asset. Follow these steps:

1. Right-click in the **Project** window and select **Create** > **2D** > **Physics (Core)** > **Area**.
2. Select the shape you want to create, for example **Circle Geometry**.
3. Select the asset Unity creates in the **Project** window, then adjust the properties in the **Inspector** window.
4. In the **Inspector** window of any Physics Area component that matches the geometry type, drag the geometry asset into the **Geometry Asset** property, or select the picker (**⊙**).

For the full list of shapes, refer to [Physics Pose and Physics Area components](/engine/6000.7/manual/unity2d/2d-physics-api/create-objects/pose-and-area.md).

## Save a set of existing properties

To create a definition asset or geometry asset with the current properties of a component, follow these steps:

1. Select the GameObject with the component you want to create a definition from.
2. In the **Inspector** window, next to the relevant **Asset** field, select **Make Asset**.
3. Save the asset.

To stop a component using a shared asset and revert it to using its own local properties, select **Make Local**.

## Change the default definitions

To change the default values of a component, follow these steps:

1. Create and assign a Physics Core Settings 2D asset. For more information, refer to [Configure global 2D Physics Core settings](/engine/6000.7/manual/unity2d/2d-physics-api/properties/class-physics-core-settings2d.md).
2. In the Editor window, select **Physics Core 2D** > **Settings**.
3. Configure the properties in the **Default Definitions** tab.

Unity uses the default values for components that don't have a definition asset assigned, and for a newly created definition asset.

For a full list of properties, refer to [Physics Core 2D reference](/engine/6000.7/manual/unity-editor/editor-settings-reference/comp-manager-group/class-physics-core2dproject-settings.md).

## Additional resources

* [Configure 2D Physics Core scenes](/engine/6000.7/manual/unity2d/2d-physics-api/properties.md)
* [Pin properties in 2D Physics Core](/engine/6000.7/manual/unity2d/2d-physics-api/properties/pin-properties.md)
* [Attach custom data to 2D Physics Core objects](/engine/6000.7/manual/unity2d/2d-physics-api/properties/custom-data.md)
* [PhysicsCore2D repository](https://github.com/Unity-Technologies/PhysicsExamples2D/tree/master) on GitHub