Ep 7: Universal IDs: UID2, ID5, SharedID

Chrome kept cookies. So why do buyers still want IDs.

Safari blocks third party cookies by default, and Firefox isolates them per site. A universal ID is one identifier many buyers can read.

Three, on news.example. Shared ID. Prebid stores a random ID in a first party cookie on your domain. Free, no login, but it only works on your site. ID five. You get a partner number, and ID five returns an encrypted ID from signals your page shares, like a hashed email, that works across sites. UID2, open source, from The Trade Desk. It starts from a logged-in email or phone number, hashed, salted and turned into a rotating encrypted token. Readers can opt out any time. All three ride in the bid request’s extended IDs list, tagged by source.

Today, ask which IDs your stack sends, and how many of your readers are logged in.

Next… Prebid identity modules in plain language.