Awake vs Start execution order in Unity - Visual Side-by-Side Comparison

Concept Flow - Awake vs Start execution order

GameObject Created

↓

Awake Called on All Scripts

↓

Start Called on Enabled Scripts

↓

Game Starts Running

Unity calls Awake first on all scripts when the object is created, then calls Start on enabled scripts before the game begins running.

Execution Sample

Unity

void Awake() {
    Debug.Log("Awake called");
}

void Start() {
    Debug.Log("Start called");
}

This code logs messages showing when Awake and Start methods are called during Unity's execution order.

Execution Table

Step	Method Called	Script State	Action	Output
1	Awake	All scripts initialized	Initialize variables, setup references	"Awake called" logged
2	Awake	Next script initialized	Initialize variables, setup references	"Awake called" logged
3	Start	Scripts enabled	Begin gameplay logic	"Start called" logged
4	Start	Next script enabled	Begin gameplay logic	"Start called" logged
5	Game Running	All scripts ready	Gameplay proceeds	No further Awake or Start calls

💡 All Awake methods run first on all scripts, then all Start methods run on enabled scripts before gameplay continues.

Variable Tracker

Variable	Before Awake	After Awake	After Start	Final
isInitialized	false	true	true	true
isReady	false	false	true	true

Key Moments - 2 Insights

Why does Awake run before Start on all scripts instead of running Awake and Start on one script before moving to the next?

Unity calls Awake on all scripts first to ensure all objects are initialized before any Start method runs, as shown in execution_table steps 1-2 (Awake) then 3-4 (Start).

What happens if a script is disabled when Awake runs?

Awake still runs on disabled scripts to initialize them, but Start only runs on enabled scripts, as seen in execution_table where Start runs only on enabled scripts.

Visual Quiz - 3 Questions

Look at the execution_table, at which step does the first Start method run?

A Step 3

B Step 2

C Step 1

D Step 5

💡 Hint

Check the 'Method Called' column for 'Start' and see which step it first appears.

According to variable_tracker, when does 'isReady' become true?

A After Awake

B Before Awake

C After Start

D Never

💡 Hint

Look at the 'isReady' row and see when its value changes to true.

If a script is disabled, which method will still run according to the execution flow?

A Neither Awake nor Start

B Awake only

C Start only

D Both Awake and Start

💡 Hint

Refer to the key_moments section explaining Awake runs on disabled scripts but Start does not.

Concept Snapshot

Awake runs first on all scripts when objects are created.
Start runs after Awake only on enabled scripts.
Awake is for initialization; Start is for gameplay setup.
Awake always runs before any Start.
Disabled scripts run Awake but not Start.

Full Transcript

In Unity, when a game starts, the Awake method is called first on all scripts attached to game objects. This happens even if the scripts are disabled. Awake is used to initialize variables and set up references. After all Awake methods have run, Unity calls the Start method on all enabled scripts. Start is used to begin gameplay logic. This order ensures all objects are ready before gameplay begins. The execution table shows Awake calls first on all scripts, then Start calls. Variables like isInitialized become true after Awake, while isReady becomes true after Start. If a script is disabled, Awake still runs but Start does not. This helps avoid errors from uninitialized objects during gameplay.

Practice

1. In Unity, which method is called first when a scene loads: Awake or Start?

easy

A. Awake is called before Start.

B. Start is called before Awake.

C. Both are called at the same time.

D. Neither is called automatically.

Solution

1. Step 1: Understand Unity's initialization order

   Unity calls Awake first to initialize objects early.

2. Step 2: Recognize Start timing

   Start runs after Awake, before gameplay begins.

3. Final Answer:

   Awake is called before Start. -> Option A

4. Quick Check:

   Awake runs first = D [OK]

Hint: Remember: Awake sets up early, Start sets up later [OK]

Common Mistakes:

• Thinking Start runs before Awake
• Believing both run simultaneously
• Assuming methods need manual calls

2. Which of the following is the correct syntax to define the Awake method in a Unity C# script?

easy

A. public void awake() { }

B. private Awake() { }

C. void Awake() { }

D. Awake() => { }

Solution

1. Step 1: Recall Unity method syntax

   Unity calls Awake automatically if defined as void Awake().

2. Step 2: Check access modifiers

   Awake is usually private by default, so void Awake() is correct and common.

3. Final Answer:

   void Awake() { } -> Option C

4. Quick Check:

   Use void Awake() syntax [OK]

Hint: Awake method is usually defined as void Awake() [OK]

Common Mistakes:

• Adding public or private explicitly (not required)
• Using arrow syntax which is invalid here
• Omitting return type

3. Consider this Unity script attached to a GameObject:

void Awake() { Debug.Log("Awake called"); }
void Start() { Debug.Log("Start called"); }

What will be the order of messages in the Console when the scene starts?

medium

A. Only "Awake called" appears

B. "Start called" then "Awake called"

C. Only "Start called" appears

D. "Awake called" then "Start called"

Solution

1. Step 1: Identify method call order

   Unity calls Awake first, so "Awake called" logs first.

2. Step 2: Confirm Start runs after Awake

   Then Start runs, logging "Start called" second.

3. Final Answer:

   "Awake called" then "Start called" -> Option D

4. Quick Check:

   Awake logs first, Start logs second [OK]

Hint: Awake logs before Start logs in console [OK]

Common Mistakes:

• Assuming Start logs before Awake
• Thinking only one method logs
• Confusing method call timing

4. You wrote this script but Start never runs:

void Awake() { Debug.Log("Awake"); }
void start() { Debug.Log("Start"); }

What is the problem?

medium

A. Awake prevents Start from running.

B. start method name is lowercase, should be Start.

C. The script is missing public keyword on Start.

D. Unity does not call Start automatically.

Solution

1. Step 1: Check method names for case sensitivity

   Unity requires exact method names; Start must be capitalized.

2. Step 2: Understand Unity's method calling rules

   Lowercase start is ignored, so Start never runs.

3. Final Answer:

   start method name is lowercase, should be Start. -> Option B

4. Quick Check:

   Method names are case-sensitive [OK]

Hint: Check method names are exactly capitalized [OK]

Common Mistakes:

• Assuming Awake blocks Start
• Thinking public keyword is required
• Believing Unity calls lowercase methods

5. You have two scripts on different GameObjects:

Script A:
void Awake() { Debug.Log("A Awake"); }
void Start() { Debug.Log("A Start"); }

Script B:
void Awake() { Debug.Log("B Awake"); }
void Start() { Debug.Log("B Start"); }

What is the correct order of messages in the Console when the scene starts?

hard

A. "A Awake", "B Awake", "A Start", "B Start"

B. "A Awake", "A Start", "B Awake", "B Start"

C. "A Start", "B Start", "A Awake", "B Awake"

D. "B Awake", "A Awake", "B Start", "A Start"

Solution

1. Step 1: Understand Awake runs on all objects first

   Unity calls all Awake methods before any Start methods.

2. Step 2: Recognize Start runs after all Awake calls

   After all Awake calls, Unity calls all Start methods.

3. Final Answer:

   "A Awake", "B Awake", "A Start", "B Start" -> Option A

4. Quick Check:

   All Awake first, then all Start [OK]

Hint: All Awake run before any Start runs [OK]

Common Mistakes:

• Thinking Awake and Start alternate per object
• Assuming Start runs before Awake
• Believing order between objects is random