public Vector3 position { get; set; }

Rigidbody.position allows you to get and set the position of a Rigidbody using the physics engine. If you change the position of a Rigidbody using Rigidbody.position, the transform will be updated after the next physics simulation step. This is faster than updating the position using Transform.position, as the latter will cause all attached Colliders to recalculate their positions relative to the Rigidbody.

If you want to continuously move a rigidbody use Rigidbody.MovePosition instead, which takes interpolation into account.

using UnityEngine;using System.Collections;public class ExampleClass : MonoBehaviour{    void Start()    {        GetComponent<Rigidbody>().position = Vector3.zero;    }}