What is an Ad Exchange?
An Ad exchange is a digital platform or place, where merchants and affiliates meet. They can sell and buy ad inventory and make a deal there. This trade and prices are based on real-time auctions and bidding.
The trade happens automatically. Merchants join to ad exchange through Demand Side Platform. They buy impressions and then resell them to buyers. Affiliates create impressions through Supply Side Platform.
There also exists an open exchange, which is accessible for every buyer and private marketplace, where merchants are invited.