Why Start and Update methods in Unity? - Purpose & Use Cases

The Big Idea

What if your game could update itself smoothly without you writing endless loops?

The Scenario

Imagine you want to make a game where a character moves and reacts to the player's input. Without special methods, you would have to write code that constantly checks for input and updates the character's position manually, over and over again.

The Problem

Doing this manually means you must write repetitive code that runs every frame, which is slow and easy to mess up. You might forget to update something or cause the game to freeze because the code runs too much or at the wrong time.

The Solution

The Start and Update methods in Unity solve this by giving you a simple way to run code once at the beginning (Start) and then repeatedly every frame (Update). Unity calls these methods automatically, so you don't have to manage the timing yourself.

Before vs After

✗ Before

void MoveCharacter() {
  // manually call this every frame
  if (Input.GetKey(KeyCode.RightArrow)) {
    position.x += speed;
  }
}

// You must remember to call MoveCharacter() yourself

✓ After

void Start() {
  // initialize variables here
}

void Update() {
  // automatically called every frame
  if (Input.GetKey(KeyCode.RightArrow)) {
    position.x += speed;
  }
}

What It Enables

This lets you focus on what your game does, while Unity handles when to run your code, making your game smooth and responsive.

Real Life Example

In a racing game, Start sets the car's starting position, and Update moves the car forward every frame based on player input, creating smooth driving controls.

Key Takeaways

Start runs once at the beginning to set things up.

Update runs every frame to keep the game moving and reacting.

Unity calls these methods automatically, saving you from manual timing.