It lets the physics system take responsibility for motion, forces, gravity, velocity, and collision response.
Why a Rigidbody Exists
A Transform says where an object is.
A Rigidbody says how physics should move it.
That distinction is important. If an object is meant to be pushed, fall, bounce, collide, or be moved by forces, it usually needs a Rigidbody.
Rigidbody and Collider
A Rigidbody and a Collider solve different parts of physics.
The Rigidbody is the body that can move through physics.
The Collider is the shape used for contact.
An object can have both:
Rigidbody2Dsays the object participates in 2D physics motionBoxCollider2DorCircleCollider2Dsays what shape the object uses for collision
For many gameplay objects, the pair is what makes physics feel real.
When You Need One
Use a Rigidbody when an object should:
- move with velocity
- respond to gravity
- receive forces or impulses
- produce collision callbacks as a moving physics object
- be queried as part of the physics simulation
You may not need a Rigidbody for static scenery that never moves. Static colliders can still define walls, floors, or trigger zones.
Rigidbody Is Not the Sprite
A Rigidbody does not draw anything.
The visible artwork usually comes from a Sprite Renderer, Model Renderer, or another rendering component.
The Rigidbody is about motion and physics behavior.