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

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

My first Unity script? I was hyped. Like, finally coding a game.
Dropped some code in Start(). Hit Play.

…nothing.

The cube showed up, the scene was fine, but my code? Dead silent. Not even a log.

So I was like, “ok maybe I did it wrong.” Threw the same code into Update().
Hit Play. Boom, it worked. 🎉
But also… it wouldn’t stop. Just kept spamming like it was on loop.

And that’s when it clicked: Start() and Update() aren’t the same at all. They look similar, but they live totally different lives.

Start() — runs once

Think of Start() as the wake-up call. Fires a single time when the GameObject comes alive. That’s it.

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

Stuff it’s actually good for:

• Setting player health.

• Spawning enemies when the level begins.

• Playing an intro sound.

It’s like the setup crew — they do their job and leave.

Update() — runs forever

Update() is Unity’s heartbeat. It ticks every single frame while the object’s active.

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

What it’s good for:

• Moving characters.

• Checking inputs.

• Updating scores, timers, UI.

If it needs to keep running, this is where it goes.

My “aha” cube

Here’s the script that made me get it:

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);
    }
}

What happens:

• Game starts → cube spawns somewhere random. (Start() did that.)

• While it runs → cube drifts right forever. (Update() doing laps.)

That’s when it finally clicked for me.

My tiny cheat sheet

• Start() = one-time setup.

• Update() = constant loop.

Or if you like it simple:

• Start = first impression.

• Update = daily grind.

Wrap up

The trick isn’t picking one over the other. It’s knowing when to use which.
Start() sets the stage.
Update() keeps the play going.

And yeah, the first time I saw my cube spawn randomly and slide away… I just sat there grinning like:

“Alright. I can actually make a game.” 😅