# First-Party Data

> Get answers about first party data. Understand the key concepts and how they apply to your conversion tracking setup for optimal performance and tracking accuracy.

First-party and third-party cookies are set to track user behavior. They serve similar purposes but are set, collected, and blocked in different ways.

## First-Party Cookies

First-party cookies are set by the website you visit. They enable website owners to collect analytics data, remember user settings, and improve user experience.

When a user signs into Amazon, the browser requests the user's identity. The browser stores this cookie under the "amazon.com" domain. Without first-party cookies, users would need to sign in every time they visited, and shopping carts would reset after each item.

## Third-Party Cookies

Third-party cookies are created by domains you are not visiting. They are placed on websites through ad platform scripts and tags. Third-party cookies are accessible on any website that loads the third-party server's code.

When browsing Amazon, a user views shoes they don't purchase. Later, they see ads for those same shoes on other websites. This is third-party cookie tracking—the data persists even after closing the browser.

## Key Differences

| Aspect | First-party | Third-party |
| --- | --- | --- |
| **Set by** | Publisher's server or website JavaScript | Third-party `API` or ad platform code |
| **Availability** | Only on the originating domain | On any website loading the third-party code |
| **Browser support** | All browsers; user can delete | Most browsers; blocked by default |

## AnyTrack Cookies

AnyTrack sets these first-party cookies on your domain:

| Identifier  | Example value       | Description                                                                                                                                                                                                    |
| :---------- | :------------------ | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `_atcid`    | `as9d8f0a98f`       | Unique anonymous identifier set on the visitor's browser. This cookie has a two years TTL (time to live) and is used to track the visitor's actions, sessions and attribute them to campaigns and conversions. |
| `_atcid-pt` | `1677855987888`     | Timestamp of the session                                                                                                                                                                                       |
| `_atutm`    | campaign parameters | Stores the last campaign parameter the visitor came from                                                                                                                                                       |

## Related Articles

- [Install AnyTrack Tag](/docs/install-anytrack-tag)
- [AnyTrack Alternatives](/docs/anytrack-alternatives)
- [Conversion Attribution Matrix](/docs/conversion-attribution-matrix)