The real reason server-side bidding earns less per bid

The real reason server-side bidding earns less per bid

Client-side means the auction runs in the reader's browser. Server-side means it runs on a remote machine your page calls.

Why it matters: in the browser, buyers can read their cookie (the file that says "I know this user"). On a server, that link often breaks, so buyers bid blind, and a blind buyer bids less.

Tiny example: same user, same slot. Client-side a buyer pays $2.50 because they recognize them. Server-side they pay $1.10 because they don't.

One thing to try: run a few partners client-side and a few server-side, then compare their average bid, not just total revenue.

In plain English: server-side is faster but the buyer often can't see who they're bidding on.