Here are some documentation links:
Compare new visitors to return visitors
Some other threads about the same:
New Visitors (more than one visit)
A unique visitor can be identified in the following ways in Adobe Analytics (data feed documentation):
Analytics Visitor IDs
There are several ways a visitor can be identified in Analytics (listed in the following table in order of preference):
In many scenarios you might see 2 or 3 different IDs on a call, but Analytics will use the first ID present from that list as the official visitor ID, and split that value across the post_visid_high and post_visid_low columns. For example, if you are setting a custom visitor ID (included in the "vid" query parameter), that ID will be used before other IDs that might be present on that same hit.
In terms of cookies it depends if you have implemented the Visitor ID services or not but the general guidance for cookie expiration can be found here:
Analytics Cookies
Cookie Name: s_vi
Attribute | Description |
|---|
Information Stored | Unique visitor ID time/date stamp |
Expiration | 2 years |
Usage | This cookie is used to identify a unique visitor |
Location | This cookie is stored at the domain of the image request - typically 2O7.net if you are using third-party cookies, or your domain if using first-party cookies. |
Size | 44 bytes |
Note: Each Analytics visitor ID is associated with a visitor profile on Adobe servers. Visitor profiles are deleted after 1 year of inactivity regardless of any visitor ID cookie expiration.
Cookie Name: s_fid
Attribute | Description |
|---|
Information Stored | Fallback unique visitor ID time/date stamp |
Expiration | 5 years |
Usage | This cookie is used to identify a unique visitor if the standard s_vi cookie is unavailable due to third-party cookie restrictions. Not used for implementations that use first-party cookies. |
Location | This cookie is stored on your domain as a first-party cookie. |
Size | 33 bytes |
Cookie Name: AMCV_###@AdobeOrg
The Visitor ID service uses JavaScript to store a unique visitor ID in an AMCV_###@AdobeOrg cookie on the domain of the current website, where ### represents a random string of characters. For example, AMCV_1FD6776A524453CC0A490D44%40AdobeOrg. See also, Cookies and the ID Service.
Attribute | Description |
|---|
Information Stored | Unique visitor IDs used by Experience Cloud Solutions. |
Expiration | 2 years |
Usage | This cookie is used to identify a unique visitor |
Location | This cookie is stored at the domain of the website (not the domain of the image request). |
Size | Varies, most customers can expect this cookie to be around 200 bytes in length. |
Please be aware that the cookies expiration can be changed in the implementation from the default expiration using:
s.cookieLifetime for s_vi cookies
cookieLifetime for AMCV_ cookies