🎮 Unity C# Basics: Start() vs Update()

🚪 My First “Wait, Why Didn’t That Run?” Moment

When I wrote my first Unity script, I proudly put my code inside Start().

Hit Play.
Nothing happened.

Then I tried Update().
Boom — it worked. But it kept running forever.

That’s when I realized: these two methods aren’t the same at all. They look similar, but they live very different lives

Start() Explained

Think of Start() as your “one-time setup.”
It runs once, the moment your GameObject becomes active.

void Start()
{
    Debug.Log("I run once at the beginning 🚀");
}

Perfect for things like:

• Setting a player’s starting health ❤️

• Spawning enemies at the beginning 👾

• Playing an intro sound 🎵

🔄 Update() Explained

Meanwhile, Update() is Unity’s heartbeat.
It runs every single frame while the GameObject is active.

void Update()
{
    Debug.Log("I run every frame 🔄");
}

Perfect for things like:

• Moving a character 🕹️

• Checking for player input ⌨️

• Updating score or UI in real time 🎯

🏃 A Quick Example

Let’s say you want a cube to:

1. Start at a random position (set once at the beginning).

2. Keep moving right (every frame).

using UnityEngine;

public class StartVsUpdate : MonoBehaviour
{
    void Start()
    {
        transform.position = new Vector3(Random.Range(-5, 5), 0, 0);
        Debug.Log("Cube spawned at a random spot 🎲");
    }

    void Update()
    {
        transform.Translate(Vector3.right * Time.deltaTime);
    }
}

👉 Run this, and your cube appears somewhere random — then slides right forever.
That’s Start vs Update in action.

⚡ Quick Cheat Sheet

• Start() = Runs once at the beginning. Great for setup.

• Update() = Runs every frame. Great for continuous logic.

Or in plain English:
Start is your “first impression.”
Update is your “daily grind.”

🎯 Wrapping Up

The trick isn’t to pick Start or Update — it’s knowing when to use each.
Start handles your one-time prep.
Update powers your moment-to-moment gameplay.