> For the complete documentation index, see [llms.txt](https://docs.intelligems.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.intelligems.io/analytics/custom-events/overview.md).
# Overview
You can use custom events to measure user behavior during experiments that are not covered by built-in metrics. Events can be created and managed in the [Events Manager](https://app.intelligems.io/events-manager).
There are two categories of custom events: those that track page visits, and those that track other user interactions on the site.
They measure different things — and, importantly, they differ in **when you can add them to a test**:
| | Page visit events | User interaction events |
| -------------- | ---------------------------------------------- | -------------------------------------------------------------- |
| Measures | Visitors who viewed specific pages | Actions on a page (clicks, scrolls, element visibility) |
| Built on | Intelligems' page-view tracking | A live listener on the page |
| Retroactive? | **Yes** — covers traffic that already happened | **No** — only captures interactions that occur while it's live |
| When to set up | Anytime, even after a test has started | Before the traffic you want to measure |
## Page visits
These events measure or filter to visitors who visited specific pages. Because they use Intelligems' built-in page view tracking, they are **retroactive** — the data already exists, so you can add them to an experiment even after it has started and still see results for earlier traffic.
## User Interaction
These events measure user interactions on your site — for example, clicks or scrolls on a page. They rely on a listener that records interactions only while the event is live, so they are **not retroactive**: set them up before the traffic you want to measure, or interactions that happened earlier won't be captured.
Separately, the targeted element itself doesn't need to exist when the page first loads. Elements created dynamically afterward (for example, by an app) can still be tracked — that's about *where* the element appears, not *when* you configure the event.
{% hint style="success" %}
Custom Metrics can be added to Tests and Personalizations via the Configure Analytics tab
{% endhint %}
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