GA4 and Google Tag Manager come with their own vocabulary, and some of it changed recently. These are the terms that come up most often, in plain English, with a link to the guide that goes deeper.
Collecting data.
- Property
- The home for a business's data in GA4, holding its settings, data streams and reports. An account can hold several properties.
- Data stream
- A source of data for a GA4 property: a website, an iOS app or an Android app. Each website stream has a measurement ID starting
G-. - Event
- Everything GA4 records is an event: a page view, a scroll, a form sent, a purchase. Each has a name and can carry parameters.
- Parameter
- A detail sent with an event, such as the page address or a purchase's value. Your own parameters only appear in reports once registered as custom dimensions or metrics.
- Custom dimension
- A parameter registered in GA4's admin settings, so it can be used in reports and explorations. Standard properties allow 50 event-scoped and 25 user-scoped custom dimensions.
- Recommended event
- An event name Google has defined, such as
purchaseorgenerate_lead, with the parameters it expects. GA4 only recognises the exact name: the event name checker spots near misses. - Enhanced measurement
- A GA4 setting that records some events without extra setup: page views, scrolls, outbound clicks, site search, video engagement, file downloads and form interactions.
- dataLayer
- A list on each page that the website fills with facts, such as a purchase and its items, for Tag Manager to read. Tracking built on it is far sturdier than tracking that reads the page. See the dataLayer specification template.
- Google Tag Manager
- Google's free tool for managing tracking code. A container holds tags, the code that sends data; triggers, which say when each tag runs; and variables, the values tags use. See Google Tag Manager consultant.
- Google tag
- Google's single piece of code for GA4 and Google Ads, also called gtag.js. It can run on its own or through Google Tag Manager.
- Cross-domain tracking
- Settings that keep one visitor's session together when they move between your domains, such as a shop and a separate checkout. See cross-domain tracking in GA4.
- Server-side tagging
- Sending tracking data first to a server you control, which passes it on to GA4 and other platforms. It gives control over what leaves your site. See server-side GTM.
- Google tag gateway
- Serving Google's tags through your own domain, using your content delivery network. A lighter option than server-side tagging. See Google tag gateway vs server-side GTM.
- Measurement Protocol
- A way to send events to GA4 straight from a server, for things that don't happen in a browser, such as refunds or sales completed offline.
Key events and conversions.
- Key event
- An event marked as important in GA4, such as a purchase or an enquiry. Key events were called conversions until March 2024. See key events vs conversions.
- Conversion
- In Google Ads, an action counted for bidding and reporting. GA4 key events can be imported into Google Ads as conversions, so the two names now mean different things.
- Transaction ID
- The unique order number sent with a purchase. GA4 uses it to spot the same purchase sent twice. See fixing duplicate key events.
- Enhanced conversions
- A Google Ads feature that sends first-party details, such as an email address, in hashed form with a conversion, so Google can match it to an ad click more often.
Traffic and attribution.
- Session
- A group of one visitor's interactions. By default a session ends after 30 minutes without activity.
- Engaged session
- A session that lasted longer than 10 seconds, included a key event, or had at least two page views.
- Engagement rate
- The share of sessions that were engaged sessions. GA4's bounce rate is the opposite: the share that weren't.
- Default channel group
- GA4's rules for sorting traffic into channels such as Organic Search, Paid Search, Email and Direct, based on the source, medium and campaign.
- UTM parameters
- Tags added to a link, such as
utm_source,utm_mediumandutm_campaign, that tell GA4 where a visit came from. See the UTM guide and the UTM builder. - Direct
- Sessions that arrive with no referrer and no campaign information. Much of it is traffic GA4 couldn't trace. See Direct traffic in GA4.
- Unassigned
- Sessions GA4 couldn't match to any channel rule, usually because of missing or unusual campaign tags. See Unassigned traffic in GA4.
- (not set)
- What GA4 shows when a value is missing, such as a landing page for a session that started without a page view. See (not set) landing pages.
- Unwanted referrals
- A GA4 setting listing domains that shouldn't count as the source of a visit, such as payment providers a customer returns from.
- Attribution model
- The rule for sharing credit for key events between channels. GA4 uses data-driven attribution by default, with last-click models as the alternative.
Consent and privacy.
- Consent Mode v2
- Google's way for its tags to follow each visitor's cookie choice, using four signals:
ad_storage,analytics_storage,ad_user_dataandad_personalization. See Consent Mode v2. - Basic and advanced Consent Mode
- Basic holds Google's tags back until the visitor agrees. Advanced loads them and, if the visitor refuses, sends cookieless pings that Google uses for modelling. See basic or advanced.
- Consent management platform
- The software that shows the cookie banner, records each visitor's choice and passes it to your tags.
- Modelled data
- Estimates GA4 makes of activity from visitors who refused analytics cookies, based on those who accepted. It only appears once a property has enough data.
- Google signals
- A GA4 setting that uses data from signed-in Google users for reporting across devices and for demographics. Turning it on can cause thresholding.
- Thresholding
- GA4 hiding rows in a report when the numbers are small enough that people might be identified, often when Google signals is on.
- Data retention
- How long GA4 keeps event-level data for explorations: 2 or 14 months on standard properties. Standard reports aren't affected.
Reporting and data.
- Exploration
- GA4's area for custom analysis: free-form tables, funnels, paths and segments. Large explorations can be sampled.
- Sampling
- GA4 analysing a subset of the data and scaling up the results, which can happen in explorations over large date ranges.
- Content group
- A dimension that groups pages into sections, such as products, guides or support, so they can be compared. This site uses them.
- BigQuery export
- A free GA4 feature that copies every raw event into Google's BigQuery data warehouse, for analysis GA4 can't do. See connecting GA4 to BigQuery.
- Data Studio
- Google's free dashboard tool, which reads GA4, BigQuery, Google Ads and other sources. See custom GA4 dashboards.
- Measurement plan
- A document agreeing what to track and why: the business outcomes, the key events and who owns them. See the measurement plan template.
A term missing, or a number in GA4 that doesn't make sense? The GA4 mini audit checks your setup and explains what it finds in plain English.