Rigidbodies
Rigidbodies move based on physical forces applied to them, such as gravity and collisions. Typical rigidbodies are boxes, balls, furniture, and so on — objects that are pushed, pulled, and knocked around, and also have effects on other rigidbodies they collide with.
In the Property Grid, click Add component and select Rigidbody.
Next to Collider Shapes, click (Add) and select the shape you want.