January 20266 min read

Event Tracking

Master GA4's event-based model: automatic events, enhanced measurement, custom events, and parameters.

The Event Model

GA4's event-based model is fundamentally different from Universal Analytics:

code

Universal Analytics:
User → Session → Pageview/Event

GA4:
User → Events (everything is an event)
      ├── page_view (event)
      ├── scroll (event)
      ├── click (event)
      ├── purchase (event)
      └── custom_action (event)

Event Anatomy

Every GA4 event consists of:

| Component | Description | Example | |-----------|-------------|---------| | Event Name | What happened | purchase | | Parameters | Details about the event | value, currency, items | | User Properties | Persistent user attributes | membership_level | | Timestamp | When it occurred | Auto-captured |

Event Naming Rules

code

Rules for event names:
├── Max 40 characters
├── Must start with a letter
├── Only letters, numbers, underscores
├── Case-sensitive (purchase ≠ Purchase)
└── Cannot use reserved prefixes (ga_, google_, firebase_)

Event Limits

| Limit | Amount | |-------|--------| | Unique event names per property | 500 | | Parameters per event | 25 | | Event name length | 40 characters | | Parameter name length | 40 characters | | Parameter value length | 100 characters |

Automatic Events

These events are collected automatically without any configuration:

Core Automatic Events

| Event | Trigger | Key Parameters | |-------|---------|----------------| | first_visit | First time user visits | - | | session_start | New session begins | - | | user_engagement | 10+ seconds focused on page | engagement_time_msec | | page_view | Page loads | page_location, page_referrer, page_title |

Session Definition in GA4

code

A new session starts when:
├── First visit ever
├── 30+ minutes of inactivity
├── Midnight (in property timezone)
└── Campaign source changes (UTM parameters)

Engaged Sessions

code

A session is "engaged" when ANY of:
├── Duration > 10 seconds
├── 2+ page views
└── 1+ conversion event

Key Metric: Engagement rate (engaged sessions / total sessions) replaces UA's bounce rate. Higher is better.

Enhanced Measurement

Enhanced Measurement events can be toggled on/off in the Admin interface.

How to Enable

code

Admin → Data Streams → Select stream → Enhanced measurement → Toggle events

Available Enhanced Measurement Events

| Event | What It Tracks | Parameters | |-------|----------------|------------| | page_view | Page loads + history changes | page_location, page_title | | scroll | 90% vertical scroll depth | - | | outbound_click | Clicks to other domains | link_url, link_domain, outbound | | site_search | Internal site searches | search_term | | video_start | Embedded video starts | video_title, video_provider, video_url | | video_progress | 10%, 25%, 50%, 75% progress | video_percent, video_current_time | | video_complete | Video ends | video_duration | | file_download | File downloads | file_name, file_extension, link_url | | form_start | First form interaction | form_destination, form_id | | form_submit | Form submission | form_destination, form_id, form_submit_text |

Best Practices

code

□ Enable all relevant Enhanced Measurement events
□ Test each event in DebugView after enabling
□ Note: Video tracking works for YouTube embeds only
□ File download detects common extensions (.pdf, .doc, etc.)
□ Site search requires consistent URL parameter

Recommended Events

Google provides recommended event names for common use cases. Using these unlocks special reporting features.

E-commerce Events

| Event | When to Use | |-------|-------------| | view_item_list | User views a list of products | | view_item | User views a product detail page | | add_to_wishlist | User adds to wishlist | | add_to_cart | User adds product to cart | | remove_from_cart | User removes product from cart | | begin_checkout | User starts checkout | | add_payment_info | User submits payment info | | add_shipping_info | User submits shipping info | | purchase | User completes purchase | | refund | Order is refunded |

Lead Generation Events

| Event | When to Use | |-------|-------------| | generate_lead | User submits lead form | | sign_up | User creates account | | login | User logs in | | share | User shares content |

Engagement Events

| Event | When to Use | |-------|-------------| | search | User searches | | view_search_results | Search results displayed | | select_content | User selects content | | select_item | User selects item from list | | select_promotion | User clicks promotion | | view_promotion | Promotion is viewed |

Why Use Recommended Events?

code

Benefits of recommended events:
├── Automatic e-commerce reports
├── Predictive metrics eligibility
├── Cross-platform consistency
├── Future feature compatibility
└── Better Google Ads integration

Custom Events

For actions not covered by automatic, enhanced, or recommended events.

Creating Custom Events

Method 1: gtag.js (Direct Code)

code

// Basic custom event
gtag('event', 'video_watched', {
  'video_name': 'Product Demo',
  'video_duration': 120
});

// Event with more parameters
gtag('event', 'pricing_page_interaction', {
  'plan_selected': 'enterprise',
  'billing_period': 'annual',
  'price_viewed': 299
});

Method 2: Google Tag Manager

code

1. Create GA4 Event tag
2. Set Event Name
3. Add Event Parameters
4. Create trigger (button click, form submit, etc.)
5. Test in Preview mode
6. Publish

Method 3: GA4 Interface (Modify Existing Events)

code

Admin → Events → Create event

Example: Create "signup_complete" from "page_view"
├── Matching conditions:
│   └── page_location contains "/thank-you"
└── New event name: signup_complete

Custom Event Best Practices

code

## Naming Conventions

□ Use snake_case (video_start, not videoStart)
□ Be descriptive but concise
□ Group related events with prefixes (form_start, form_submit)
□ Don't duplicate recommended event names
□ Keep under 40 characters

## Implementation

□ Always test in DebugView first
□ Document all custom events
□ Include relevant parameters
□ Register parameters as custom dimensions if needed for reports

Event Parameters

Parameters provide context and details about events.

Parameter Types

| Type | Scope | Example | |------|-------|---------| | Event Parameters | Single event | value, currency | | User Properties | All events for user | membership_tier | | Item Parameters | E-commerce items | item_name, price |

Common Parameters

code

// Event with standard parameters
gtag('event', 'purchase', {
  'transaction_id': 'T12345',
  'value': 99.99,
  'currency': 'USD',
  'tax': 8.99,
  'shipping': 5.99,
  'items': [{
    'item_id': 'SKU123',
    'item_name': 'Product Name',
    'price': 85.01,
    'quantity': 1
  }]
});

Registering Custom Parameters

To see custom parameters in reports, register them as custom dimensions/metrics:

code

Admin → Custom definitions → Create custom dimension

Name: Plan Selected
Scope: Event
Description: The pricing plan user selected
Event parameter: plan_selected

Parameter Limits

| Type | Limit | |------|-------| | Event-scoped custom dimensions | 50 | | User-scoped custom dimensions | 25 | | Custom metrics | 50 | | Parameter name length | 40 characters | | Parameter value length | 100 characters |

Important: You only need to register parameters as custom dimensions if you want to use them in standard reports. Explorations can access unregistered parameters.

January 20266 min read

Event Tracking

Master GA4's event-based model: automatic events, enhanced measurement, custom events, and parameters.

The Event Model

GA4's event-based model is fundamentally different from Universal Analytics:

code

Universal Analytics:
User → Session → Pageview/Event

GA4:
User → Events (everything is an event)
      ├── page_view (event)
      ├── scroll (event)
      ├── click (event)
      ├── purchase (event)
      └── custom_action (event)

Event Anatomy

Every GA4 event consists of:

Event Naming Rules

code

Rules for event names:
├── Max 40 characters
├── Must start with a letter
├── Only letters, numbers, underscores
├── Case-sensitive (purchase ≠ Purchase)
└── Cannot use reserved prefixes (ga_, google_, firebase_)

Event Limits

Automatic Events

These events are collected automatically without any configuration:

Core Automatic Events

Session Definition in GA4

code

A new session starts when:
├── First visit ever
├── 30+ minutes of inactivity
├── Midnight (in property timezone)
└── Campaign source changes (UTM parameters)

Engaged Sessions

code

A session is "engaged" when ANY of:
├── Duration > 10 seconds
├── 2+ page views
└── 1+ conversion event

Key Metric: Engagement rate (engaged sessions / total sessions) replaces UA's bounce rate. Higher is better.

Enhanced Measurement

Enhanced Measurement events can be toggled on/off in the Admin interface.

How to Enable

code

Admin → Data Streams → Select stream → Enhanced measurement → Toggle events

Available Enhanced Measurement Events

Best Practices

code

□ Enable all relevant Enhanced Measurement events
□ Test each event in DebugView after enabling
□ Note: Video tracking works for YouTube embeds only
□ File download detects common extensions (.pdf, .doc, etc.)
□ Site search requires consistent URL parameter

Recommended Events

Google provides recommended event names for common use cases. Using these unlocks special reporting features.

E-commerce Events

Lead Generation Events

| Event | When to Use | |-------|-------------| | generate_lead | User submits lead form | | sign_up | User creates account | | login | User logs in | | share | User shares content |

Engagement Events

Why Use Recommended Events?

code

Benefits of recommended events:
├── Automatic e-commerce reports
├── Predictive metrics eligibility
├── Cross-platform consistency
├── Future feature compatibility
└── Better Google Ads integration

Custom Events

For actions not covered by automatic, enhanced, or recommended events.

Creating Custom Events

Method 1: gtag.js (Direct Code)

code

// Basic custom event
gtag('event', 'video_watched', {
  'video_name': 'Product Demo',
  'video_duration': 120
});

// Event with more parameters
gtag('event', 'pricing_page_interaction', {
  'plan_selected': 'enterprise',
  'billing_period': 'annual',
  'price_viewed': 299
});

Method 2: Google Tag Manager

code

1. Create GA4 Event tag
2. Set Event Name
3. Add Event Parameters
4. Create trigger (button click, form submit, etc.)
5. Test in Preview mode
6. Publish

Method 3: GA4 Interface (Modify Existing Events)

code

Admin → Events → Create event

Example: Create "signup_complete" from "page_view"
├── Matching conditions:
│   └── page_location contains "/thank-you"
└── New event name: signup_complete

Custom Event Best Practices

code

## Naming Conventions

□ Use snake_case (video_start, not videoStart)
□ Be descriptive but concise
□ Group related events with prefixes (form_start, form_submit)
□ Don't duplicate recommended event names
□ Keep under 40 characters

## Implementation

□ Always test in DebugView first
□ Document all custom events
□ Include relevant parameters
□ Register parameters as custom dimensions if needed for reports

Event Parameters

Parameters provide context and details about events.

Parameter Types

Common Parameters

code

// Event with standard parameters
gtag('event', 'purchase', {
  'transaction_id': 'T12345',
  'value': 99.99,
  'currency': 'USD',
  'tax': 8.99,
  'shipping': 5.99,
  'items': [{
    'item_id': 'SKU123',
    'item_name': 'Product Name',
    'price': 85.01,
    'quantity': 1
  }]
});

Registering Custom Parameters

To see custom parameters in reports, register them as custom dimensions/metrics:

code

Admin → Custom definitions → Create custom dimension

Name: Plan Selected
Scope: Event
Description: The pricing plan user selected
Event parameter: plan_selected

Parameter Limits

Important: You only need to register parameters as custom dimensions if you want to use them in standard reports. Explorations can access unregistered parameters.