# Collisions and interactions in the LowLevelPhysics2D API

> Enable and detect collisions between 2D physics objects, and cast rays to check for intersections.

Combine or connect shapes, and enable and detect contact between physics objects using the `LowLevelPhysics2D` API.

> **Note:**
>
> This documentation is about writing C# scripts using the `LowLevelPhysics2D` API. To use 2D physics in the Unity Editor using components like the Rigidbody 2D component, refer to [2D physics](/engine/6000.3/manual/unity2d/2d-physics.md.md) instead.

| **Topic**                                                                                                                           | **Description**                                                                                              |
| ----------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------ |
| [Introduction to collision in the LowLevelPhysics2D API](/engine/6000.3/manual/unity2d/2d-physics-api/interactions/introduction.md) | Learn about collisions between 2D physics objects, including collision types, layers, and layer masks.       |
| [Configure collisions between objects](/engine/6000.3/manual/unity2d/2d-physics-api/interactions/collisions-enable.md)              | Change which objects collide with which using layers and masks, and enable using 64 layers instead of 32.    |
| [Detect collisions between objects](/engine/6000.3/manual/unity2d/2d-physics-api/interactions/collision-handle.md)                  | To detect when collisions occur and respond to them, use collision callback methods or event methods.        |
| [Check LowLevelPhysics2D API intersections](/engine/6000.3/manual/unity2d/2d-physics-api/interactions/raycasting.md)                | To check whether 2D physics objects overlap or will collide, also known as intersections, use query methods. |

## Additional resources

* [Optimize the LowLevelPhysics2D API with multithreading](/engine/6000.3/manual/unity2d/2d-physics-api/multithreading.md)
* [PhysicsCore2D repository](https://github.com/Unity-Technologies/PhysicsExamples2D/tree/master) on GitHub