GameObject.Find() / GetComponent<T>()

using UnityEngine;

// Searches the scene for a GameObject by name (returns null if not found).
GameObject obj = GameObject.Find(string name);

// Searches for a GameObject by tag.
GameObject obj = GameObject.FindWithTag(string tag);

// Returns all GameObjects that match the given tag.
GameObject[] objs = GameObject.FindGameObjectsWithTag(string tag);

// Returns the component of type T attached to this GameObject.
T comp = GetComponent<T>();

// Searches this GameObject and its children for a component of type T.
T comp = GetComponentInChildren<T>();

// Searches this GameObject and its parents for a component of type T.
T comp = GetComponentInParent<T>();

// Adds a component of type T to this GameObject and returns it.
T comp = gameObject.AddComponent<T>();

using UnityEngine;

public class FindSample : MonoBehaviour
{
    // Assigning via the Inspector is the recommended approach.
    [SerializeField] private GameObject player;
    [SerializeField] private Rigidbody2D myRigidbody;

    void Start()
    {
        // GameObject.Find() — searches the scene by name (recommended to use in Start).
        GameObject enemy = GameObject.Find("Enemy");
        if (enemy != null)
        {
            Debug.Log($"Enemy found: {enemy.transform.position}");
        }

        // FindWithTag() — searches by tag (faster than Find()).
        GameObject cam = GameObject.FindWithTag("MainCamera");
        if (cam != null)
        {
            Debug.Log($"Main camera: {cam.name}");
        }

        // GetComponent<>() — retrieves a component.
        Rigidbody rb = GetComponent<Rigidbody>();
        if (rb != null)
        {
            rb.AddForce(Vector3.up * 10f);
        }

        // TryGetComponent — skips the null check (recommended).
        if (TryGetComponent<Animator>(out Animator anim))
        {
            anim.SetTrigger("Jump");
        }

        // GetComponentInChildren — searches child objects for the component.
        AudioSource sfx = GetComponentInChildren<AudioSource>();
        if (sfx != null)
        {
            sfx.Play();
        }

        // Retrieves multiple objects by tag.
        GameObject[] coins = GameObject.FindGameObjectsWithTag("Coin");
        Debug.Log($"Coin count: {coins.Length}");
    }
}

GameObject.Find() traverses the entire scene, so calling it every frame inside Update() will significantly hurt performance. Call it once in Start() or Awake() and cache the result in a variable. Where possible, prefer assigning references directly in the Inspector.

Accessing a component returned by GetComponent<T>() when it is null will throw a NullReferenceException. Always perform a null check, or use TryGetComponent<T>() instead. For debug output, see Debug.Log(). For Unity math functions, see Mathf.