GA4 Events Explained: Automatic, Enhanced Measurement, Recommended, and Custom

GA4's Four Event Categories

Google Analytics 4 collects events in four distinct categories, each collected differently and with different customisation options. Understanding which category an event falls into determines how it is implemented and how reliable it is.

1. Automatically Collected Events

These events fire without any configuration on your part. GA4 collects them as soon as the GA4 tag is installed:

• first_visit: first time a user opens your website or app
• session_start: beginning of a new session
• user_engagement: when a page has focus for at least one second
• page_view: every page navigation (in web)

These events are useful for basic reach and session metrics but generally should not be marked as conversions (Key Events) because they fire so frequently.

2. Enhanced Measurement Events

Enabled with a toggle in GA4 (Admin then Data Streams then Enhanced Measurement), these events are collected automatically from the page without custom code:

• scroll: when a user reaches 90% scroll depth on a page
• click: outbound link clicks (leaving your domain)
• view_search_results: when a user performs a site search
• video_start/progress/complete: for embedded YouTube videos
• file_download: when a user clicks a file download link
• form_start/submit: experimental form interaction tracking

Enhanced Measurement events are convenient but less reliable than custom events — they depend on page structure and can misfire. For critical conversions like form submissions, implement a dedicated custom event instead.

3. Recommended Events

Google defines recommended event names and parameter schemas for common action types. Using the recommended names enables automatic features in GA4 reports (like the Ecommerce reports, which only populate when you use the correct event names).

Key recommended events:

• purchase: completed transaction (requires transaction_id, value, currency, items)
• add_to_cart: product added to cart
• begin_checkout: user starts checkout process
• generate_lead: form submission or lead generation
• sign_up: user account creation
• login: user login event

Always use recommended event names where applicable — custom names for standard actions lose the built-in report integrations.

4. Custom Events

Events you define yourself for business-specific actions not covered by the recommended events. Examples:

• video_play_hero: user plays the hero video on the homepage
• calculator_used: user interacts with a pricing calculator
• tab_clicked_pricing: user clicks the pricing tab
• chatbot_opened: user opens the live chat widget

Custom events appear in GA4 reports but do not automatically populate any standard reporting views. They are best used for tracking micro-conversions and engagement signals that are specific to your business.

Event Naming Rules

All GA4 event names (including custom events) must follow these rules:

• Maximum 40 characters
• Only letters, numbers, and underscores (no spaces, no hyphens)
• Must start with a letter
• Case-sensitive: Purchase and purchase are different events
• Cannot use reserved names (e.g. ad_click, app_update, etc.)

Summary

Use automatically collected events for basic metrics. Enable enhanced measurement for passive page behaviour tracking. Use recommended event names for all standard e-commerce and lead gen actions. Add custom events for business-specific engagement signals. The combination of all four gives you a complete picture of user behaviour in GA4.

See our GA4 Setup & Audit service for proper event implementation.

Need help implementing GA4 events correctly? Contact Adslytics.