"Colliders" component in Unity Engine

Collider components
define the shape of an object for the purposes of physical collisions. A collider, which is invisible, need not be the exact same shape as the object’s mesh and in fact, a rough approximation is often more efficient and indistinguishable in gameplay.
The simplest (and least processor-intensive) colliders are the so-called primitive collider types.
In 3D, these are the Box Collider, Sphere Collider and Capsule Collider.
In 2D, you can use the Box Collider 2D and Circle Collider 2D. Any number of these can be added to a single object to create compound colliders.
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