# Browser
Site [llms.txt](/llms.txt)
---
## Browser Attributes
The web browser attributes
**Attributes:**
| Key | Stability | Value Type | Description | Example Values |
| --- | --- | --- | --- | --- |
| `browser.brands` |  | string[] | Array of brand name and version separated by a space [1] | `[" Not A;Brand 99", "Chromium 99", "Chrome 99"]` |
| `browser.document.url.full` |  | string | Absolute URL of the current browser document according to [RFC3986](https://www.rfc-editor.org/rfc/rfc3986). | `https://www.example.com/search?q=OpenTelemetry#SemConv` |
| `browser.language` |  | string | Preferred language of the user using the browser [2] | `en`; `en-US`; `fr`; `fr-FR` |
| `browser.mobile` |  | boolean | A boolean that is true if the browser is running on a mobile device [3] | |
| `browser.platform` |  | string | The platform on which the browser is running [4] | `Windows`; `macOS`; `Android` |
| `browser.web_vital.delta` |  | double | The delta between the current value and the last-reported value. See [delta](https://github.com/GoogleChrome/web-vitals?tab=readme-ov-file#report-only-the-delta-of-changes). | `0.2` |
| `browser.web_vital.id` |  | string | A unique ID representing this particular metric instance. | `v3-1677874579383-6381583661209` |
| `browser.web_vital.name` |  | string | Name of the web vital. | `cls` |
| `browser.web_vital.navigation_type` |  | string | The type of navigation, as reported by the [Navigation Timing API](https://developer.mozilla.org/docs/Web/API/PerformanceNavigationTiming/type), with additional values reported by the web-vitals library. | `navigate` |
| `browser.web_vital.rating` |  | string | The rating of the web vital value against the "good", "needs improvement", and "poor" thresholds defined for the metric. | `good` |
| `browser.web_vital.value` |  | double | Value of the web vital. | `1.0` |
**[1] `browser.brands`:** This value is intended to be taken from the [UA client hints API](https://wicg.github.io/ua-client-hints/#interface) (`navigator.userAgentData.brands`).
**[2] `browser.language`:** This value is intended to be taken from the Navigator API `navigator.language`.
**[3] `browser.mobile`:** This value is intended to be taken from the [UA client hints API](https://wicg.github.io/ua-client-hints/#interface) (`navigator.userAgentData.mobile`). If unavailable, this attribute SHOULD be left unset.
**[4] `browser.platform`:** This value is intended to be taken from the [UA client hints API](https://wicg.github.io/ua-client-hints/#interface) (`navigator.userAgentData.platform`). If unavailable, the legacy `navigator.platform` API SHOULD NOT be used instead and this attribute SHOULD be left unset in order for the values to be consistent.
The list of possible values is defined in the [W3C User-Agent Client Hints specification](https://wicg.github.io/ua-client-hints/#sec-ch-ua-platform). Note that some (but not all) of these values can overlap with values in the [`os.type` and `os.name` attributes](./os.md). However, for consistency, the values in the `browser.platform` attribute should capture the exact value that the user agent provides.
---
`browser.web_vital.name` has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.
| Value | Description | Stability |
| --- | --- | --- |
| `cls` | Cumulative Layout Shift. See [cls](https://web.dev/articles/cls). |  |
| `fcp` | First Contentful Paint. See [fcp](https://web.dev/articles/fcp). |  |
| `inp` | Interaction to Next Paint. See [inp](https://web.dev/articles/inp). |  |
| `lcp` | Largest Contentful Paint. See [lcp](https://web.dev/articles/lcp). |  |
| `ttfb` | Time to First Byte. See [ttfb](https://web.dev/articles/ttfb). |  |
---
`browser.web_vital.navigation_type` has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.
| Value | Description | Stability |
| --- | --- | --- |
| `back-forward` | Navigation through the browser's history traversal (e.g. back/forward buttons). |  |
| `back-forward-cache` | Navigation restoring a page from the back/forward cache (bfcache). |  |
| `navigate` | Navigation started by clicking a link, entering a URL, form submission, or a script operation. |  |
| `prerender` | Navigation to a page that was prerendered. |  |
| `reload` | Navigation through a reload operation or a `Location.reload()` call. |  |
| `restore` | Navigation restoring a page that was previously discarded by the browser. |  |
---
`browser.web_vital.rating` has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.
| Value | Description | Stability |
| --- | --- | --- |
| `good` | The metric value is within the "good" threshold. |  |
| `needs-improvement` | The metric value is within the "needs improvement" threshold. |  |
| `poor` | The metric value is within the "poor" threshold. |  |