---
metadata:
- name: generator
content: Diplodoc Platform v5.50.3
alternate:
- https://yandex.ru/dev/rtb/doc/en/api/user-mark.md
- https://yandex.ru/dev/rtb/doc/ru/api/user-mark.md
---
> **Documentation Index:** Fetch the complete configuration index at https://yandex.ru/dev/rtb/doc/en/llms.txt
# Tagging users
The DSP can recognize users who visit a website. This helps the DSP make conclusions about users' interests and select appropriate advertising.
When users visit websites, they can be tagged with a label containing custom data as a string of up to 200 characters. The website, the RTB host, and the DSP cooperate in this process.
1. The computer, laptop, or smartphone makes a request to the website. The site page has a “pixel” for transmitting requests to the RTB host.
2. The “pixel” sends a request from the website page to the RTB host for tagging the user. The request is not associated with ad impressions and does not initiate an auction.
3. If an error occurred, the HTTP 404 response is returned.
4. If tagging was successful, the HTTP 200 response is returned.
#### Request format:
`http://an.yandex.ru/mapuid/{dsp-name}is/{user_id}`
#### Request parameters
#|
|| **Parameter** | **Description** ||
|| dsp-name | The DSP ID on the RTB host. Please send the DSP name to your manager or write to for registration. ||
|| user_id | The user's label that the DSP inserts.
The RTB host associates the data with the user and passes the data to the DSP in the next ad impression cycle for this user (in the `buyeruid` parameter).
||
|#
#### Sample request for the AdMaster DSP
`http://an.yandex.ru/mapuid/admasteris/AE313-ASCCX-353WA`
When the browser gets a page with this kind of link, it sends a GET request to the RTB host, resulting in the data being bound to the user.