CSHARP

unity gameobject.getcomponent

rb = GetComponent<Rigidbody>();    

getcomponent unity

GameObject.GetComponent</*Component name */>();

unity GetComponent

using UnityEngine;
using System.Collections;

public class YetAnotherScript : MonoBehaviour
{
    //Create Object which get component from other Object
    //Put script and object 
    //enter Playmode to test component
    public GameObject objectToFind;

    public AudioSource audioSource;
    private void Start()
    {
        audioSource = objectToFind.GetComponent<AudioSource>();
    }
}