An ad exchange is a digital marketplace where advertisers and publishers can buy and sell advertising space in real-time. It connects various parties, including advertisers, publishers, and demand-side platforms (DSPs), allowing them to bid on ad inventory. This process helps ensure that the right ads reach the right audience at the right time. Through an ad exchange, publishers can maximize their revenue by offering their ad space to multiple advertisers simultaneously. Advertisers benefit by gaining access to a wide range of inventory across different websites and apps, making it easier to target specific audiences and optimize their advertising campaigns.