--- metadata: - name: generator content: Diplodoc Platform v5.50.3 alternate: - https://yandex.com/dev/rtb/doc/en/api/interaction.md - https://yandex.com/dev/rtb/doc/ru/api/interaction.md --- > **Documentation Index:** Fetch the complete configuration index at https://yandex.com/dev/rtb/doc/en/llms.txt # Ad impression cycle The ad impression cycle is an automated process of downloading a banner each time an HTML page is displayed on an endpoint device. 1. At the start, an endpoint device (computer, laptop, or smartphone) sends a request to the site. The site returns an HTML page with special JavaScript code. On the endpoint device, the code gets control and downloads an HTML block from the RTB host with links to advertising materials. 2. After receiving a request to display an ad, the RTB host starts an auction. 3. The RTB host sends [requests](https://yandex.com/dev/rtb/doc/en/api/web/request.md) to all potential auction participants and waits for a response for 350 ms for requests from the Russian Federation, 500 ms for international requests 1 . During this time 2 the DSP evaluates the offer and decides whether to participate in the auction. 4. If the decision is negative, the DSP responds to the RTB host's offer with HTTP 204 or HTTP 200 without the response body. 5. If the decision is positive, the DSP selects ads and bids. Then the DSP [response](https://yandex.com/dev/rtb/doc/en/api/web/response.md) is formed and sent to the RTB host. {% note info %} The DSP must send the response to the IP address that the request came from. {% endnote %} 6. After getting responses, the DSP begins comparing bids. 7. RTB host selects the highest bid from the bids made by auction participants. 8. After the amount is deducted, user impressions of the ad begin.