# Events (/docs/tracking/events)

An event is a **name** and a **scope**:

- The **name** says what happened. Use snake_case, and the [GA4 recommended names](https://support.google.com/analytics/answer/9267735) where they fit: `sign_up`, `add_to_cart`, `purchase`. The SDK warns once about any other.
- The **scope** says where or what it was about: `homepage_hero_signup`, `product_page`. It is the stable second half of the event's identity. Without one, the SDK uses the page's path.

## From the page [#from-the-page]

With the script, the client is on `window.numbers`:

```js
numbers.track('sign_up', 'footer_form')
```

With [the SDK](/docs/sdk):

```ts
numbers.track('add_to_cart', 'product_page', {
	value: 59.95,
	currency: 'EUR',
	params: { ecommerce: { items: [{ item_id: 'sku_1' }] } },
})

// At most once per key, e.g. one view_item per product.
numbers.track('view_item', 'list', { dedupeKey: 'sku_1' })
```

- `value` and `currency` are summed into revenue per variant in Improve's test results.
- `params` is any JSON object, stored with the event.

Every event also carries the page's path and UTM tags, like a [page view](/docs/tracking/page-views).

The SDK's `autoTrack()` can count three more without your own code: `outbound: true` sends `outbound_click` for links to another site, `downloads: true` sends `file_download` for links to a file, and `forms: true` sends `form_submit` for each submitted form. The scope is the element's `data-numbers-id`, or the destination, file name or form id/action. `numbers.formSubmit(form)` sends one by hand. With the script, call `numbers.autoTrack({ outbound: true })` after it loads; it replaces the script's own autoTrack, so nothing is counted twice.

Some events only the server knows, like a paid order: send those from a loader, an action or a webhook with an API token. See [events from your server](/docs/api/log#from-a-storefront).

## Limits [#limits]

- Names, scopes and other strings: at most 256 characters. Currency: at most 8 (`EUR`).
- A request body: at most 8 KB.
- Names starting with `gtm.` are refused: they are Google Tag Manager's own.
- 300 events a minute per visitor's IP and Organization. After a `429` the SDK stops sending for the `Retry-After`, or a minute.

## See what comes in [#see-what-comes-in]

**Events** in the dashboard lists every name and scope the environment received in the range, with how often, from how many visitors and when last. It is the quickest way to check a new event, or whether an Improve test's goal arrives.

A test integration can leave events you don't want to keep. The same page has **Delete events** for admins and developers: without a visitor id it removes the range's events in the selected environment, for everyone; with one it removes that visitor's events and exposures in every environment and all time, for an erasure request. Either way it brings the event registry's counts back in step. A range for everyone leaves exposures alone, so a test's Monitor still lists visitors whose events you just deleted.

A deletion that is longer than one batch deletes what it can and asks you to submit again: the page says how many went and that more remain.