Rigidbody lets a GameObject participate in 3D physics.

Important properties:

• Mass
• Linear Damping
• Angular Damping
• Use Gravity
• Is Kinematic
• Interpolate
• Collision Detection
• Constraints

Unity 6:

rb.linearVelocity
rb.angularVelocity

Forces:

rb.AddForce(
    direction * force,
    ForceMode.Acceleration
);

Controlled physical movement:

rb.MovePosition(...)
rb.MoveRotation(...)