Cookies are small piece of data that a Web server stores on a user system when the user visits a new Website. If the user accesses the same Website again, then the cookies will help the user to retain the same information accessed by them in the last visit to the Website.
- Cookie Syncing
The matching process of the SSP cookie Id to DSP cookie Id takes place through a parallel process for serving ads is known as Cookie Syncing. A cookie sync is essential because as a standard security process, the Web server of any type can only request for cookies which are set to their own domain. As the SSP sits between the end user and all DSP bidders in real-time auction although, the DSP requires a way to identify the users it is looking for.
- Importance of Cookie Syncing
Cookie syncing plays a vital role in the advertising domain for re-targeting users. Consider a scenario where an online shoes store is trying to retarget their own users. Suppose you are running an online store A and user1 comes in selects and adds one pair of $100 shoes to the shopping cart but never goes to the checkout. Now, you want to retarget that user1 and serve them an ad which directs them back to your online store to try and close the sale. As you are working with DSP1, you have a 1×1 pixel on your shopping cart page which will force the user1 to make a call to DSP1’s server as they are loading the shopping cart page giving DSP1 the chance to drop a cookie on user1. The dropped cookie is DSPcookie1.
Now, the user1 is surfing the Web, and lands on a pubnx.com that is using SSP1 to monetize their ad inventory. pubnx.com serves as a third party and redirects to SSP1, which drops a cookie on user1. This cookie is SSPcookie1. SSP1 now requests a bid from DSP1 among other bidders for the impression which SSPcookie1 is about to view. Besides this how does DSP1 knows that SSPcookie1= DSPcookie1. On the first ad, it will not know so your DSP does not bid on the impression. Remember, the SSP can only read and pass its own cookieId to the bidders.