For a long time, one of the most requested features in Google Analytics 4 was the ability to add annotations directly within reports. This option, which existed in Universal Analytics, helped add context to the data and made it easier to understand traffic spikes or drops. Since late March 2025, GA4 has finally included annotations natively.
In this article, we’ll look at what annotations in GA4 are, how to create them, how to manage them, and what kinds of annotations can be especially useful in day-to-day analysis.
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What are annotations in GA4?
Annotations in GA4 let you add notes directly within the reporting interface, linked to a specific date. They are meant to record relevant events that may have affected the data, such as marketing campaigns, website changes, or technical incidents. The idea is to leave a record of these milestones so that, when you review the data weeks or months later, the context is much easier to understand.
These annotations are visible directly in time-series reports through an icon on the timeline. When you click on the relevant date, the content of the note is displayed. This makes data interpretation much easier, especially in retrospective analysis, when you may no longer remember what happened at a specific point in time.
GA4 annotations are also useful because they are not limited to a single chart once they are created. In practice, they can be visible across reports and report cards that use line graphs, which makes them much more useful as a shared source of context for the whole property.
How to create annotations
Creating an annotation in GA4 is straightforward, and it can be done directly from the standard reports that use line charts. Google currently allows annotations to be created from reports with line graphs, and they can also be managed through the Admin area. Each property can store up to 1.000 annotations.
To create one, open the report you want to annotate and use the annotation option in the chart area. GA4 also allows you to right-click a specific data point in the line chart and add an annotation from there.
In addition to the title, GA4 lets you add a description to provide more context. You can also select a single date or a date range, and assign a color so that different types of annotations are easier to distinguish visually. The current limits are 60 characters for the title and 150 characters for the description.
Once the annotation is saved, it remains available both from the report itself and from the Admin panel. It is worth keeping in mind that not all parts of GA4 support annotations yet. At the moment, they are available in standard reports that include time-series charts. Explore reports, for example, still do not support creating or viewing annotations.
Another practical point is that if you expect to have a large number of annotations with overlapping date ranges, it is usually better to use single-date annotations where possible. That makes them easier to read and avoids overcrowding the timeline.
Best practices when naming annotations
Although GA4 lets you write any text you want in an annotation, following a clear naming convention makes a big difference. This is especially true in properties where several people work together, because a shared structure can turn annotations into a genuinely useful historical record instead of a messy collection of notes.
A common approach is to begin the annotation with a label in brackets or uppercase letters that identifies the type of event. For example, something like “[SEO] URL structure update”, “[Email] Black Friday campaign sent”, or “[Bug] Mobile checkout issues”. This makes it much easier to identify the subject of the note at a glance, even without opening the full annotation.
It can also be useful to include the initials of the responsible team or the tool involved, where relevant. For example, “[SEO][GSC] Drop in impressions due to indexing issues”. There is no need to make the system overly complicated, but a certain level of consistency helps annotations function as a kind of shared change log for the whole team.
Besides naming conventions, GA4 also lets you assign colors to annotations. This makes it possible to use one color for SEO changes, another for marketing campaigns, another for incidents, and so on. When used consistently, color coding makes the timeline much easier to scan visually.
Ideas for useful annotations
Annotations are especially valuable when they are used systematically. Rather than adding notes just for the sake of it, it makes more sense to identify the types of events that can genuinely affect the data and record them clearly. This helps explain changes in user behaviour and makes future analysis much easier.
Below are some of the situations where it can be especially useful to leave an annotation.
- Website updates: Whenever an important change is made to the website, such as a new feature, a redesign, or a usability improvement, it is a good idea to add an annotation. This helps explain possible fluctuations in traffic or conversions that may happen after the change. A simple example would be: New checkout launched.
- Marketing campaign launches: Marketing campaigns, especially large ones, often lead to traffic or conversion spikes. Leaving an annotation with the details of the campaign makes it much easier to understand later whether an increase in users or sales was driven by marketing activity or by something else. A typical example would be: Christmas campaign launched.
- SEO changes: Whenever major changes are made to SEO strategy, such as an update to URL structure, content improvements, or new on-page optimisation work, an annotation can help connect those changes to the evolution of the metrics. For example: URL structure updated.
- Technical incidents: Technical problems are another clear use case for annotations. If the website goes down, checkout breaks, the consent banner starts blocking tags, or there is a serious tracking issue, leaving an annotation can save a lot of time when reviewing the data later. These kinds of incidents often explain drops in sessions, conversions, or other key metrics.
- Tracking or implementation changes: If the GA4 setup changes, such as event tracking updates, fixes to e-commerce tracking, changes to conversion logic, or new GTM releases, it is very useful to document them in an annotation. This helps explain reporting changes that are not due to user behaviour, but to how the data is being collected.
- Product launches or pricing changes: If the business launches a new product, changes pricing, introduces a promotion, or modifies the purchase flow, these are exactly the kinds of events that should be documented. They can have a direct impact on revenue, conversion rate, and campaign performance.
- A/B tests: A/B tests should also be accompanied by annotations that record what was tested and when. This makes it much easier to interpret the impact of the experiment and compare it with previous performance. A simple example could be: A/B test on product page started.
In general, every annotation should be tied to a meaningful change or event that could affect the data being analysed. With that mindset, annotations become much more than simple notes. They become a long-term analytical aid.
Managing annotations from the Admin section
In GA4, annotations can also be managed from a dedicated section in the Admin panel. This is especially useful for teamwork, because it centralises all notes in one place regardless of who created them.
To access them, go to Admin, look for the Data display section, and open Annotations. There, you can see a list of all the notes recorded for the property. Depending on your access level, you may also be able to create, edit, delete, or export annotations from this area. Users need to be Analyst or above at property level to create, edit, or delete annotations, while Viewer or above is enough to see them.
From this section, you can carry out several actions that help keep annotations under control. You can edit existing annotations if you need to correct details or update the information. You can also delete notes that are no longer relevant or that were added by mistake. This flexibility helps keep the historical record clean and accurate.
Another advantage of managing annotations from the Admin area is the ability to sort them using different criteria, such as creation date, color, or the name of the person who created them. This becomes especially useful when the property accumulates a large volume of notes and you need to find a specific one quickly.
Annotations created in reports also appear in this list, which means everything is centralised and visible in the same place. That makes collaboration much easier and helps ensure that context is not lost over time.
Google Analytics-created annotations
In addition to user-created annotations, GA4 can also generate its own system annotations when a significant event affecting data occurs. These look similar to custom annotations, but they cannot be edited or deleted. They are there to notify users about platform-level issues or relevant data-impacting events on the corresponding date.
This can be useful because it adds another layer of context to the reports, especially when the data changes due to something happening within Google Analytics itself rather than because of a business-side change.
In the end, annotations in GA4 are a very useful feature for preserving context over time. They make it easier to record relevant events such as website changes, marketing campaigns, tracking updates, and technical incidents, which in turn makes reports easier to interpret and collaboration across teams much smoother.
