Scenes and prefabs

In plain English

A scene hierarchy is a tree of GameObjects, and the parent and child relationship lets you move and organise whole groups at once. A prefab is a reusable asset that stores a GameObject with its components and settings, so you edit it once and every copy updates. Instantiating means creating a copy of a prefab at runtime, usually from a script, and a prefab variant is a child prefab that inherits from a base prefab while overriding a few values. Prefabs matter because they keep repeated objects such as enemies and pickups consistent and easy to change.

Step by step

1. 1Create a GameObject and add the components it needs.
2. 2Drag it into the Project window to create a prefab asset.
3. 3Create a prefab variant and override one property.
4. 4Write a script that instantiates the prefab at runtime.

using UnityEngine;

public class Spawner : MonoBehaviour
{
    [SerializeField] private GameObject enemyPrefab;

    private void Start()
    {
        Instantiate(enemyPrefab, transform.position, Quaternion.identity);
    }
}

Common mistakes

• Editing a copy in the scene only changes that copy; to update every copy you must edit the prefab asset itself.
• Overriding a property on an instance breaks its link to the prefab for that property, so later prefab edits will not reach it.
• Instantiating in Update without a limit can create hundreds of objects per frame and freeze the game.
• Leaving many unused objects as separate scene copies instead of prefabs makes future changes slow and error-prone.