They also build and maintain relationships with large numbers of advertisers, to which they sell the ads inventory offered by their network of websites at various prices and on various terms. The advertisers’ ads are then displayed on either all or a variety of the sites throughout the ad network’s community of web sites to be able to best match the demographic that the advertiser has paid to focus on, which could be based around the content niche of the sites, or behavioural targeting suggestions, or other factors. As the ads are being displayed, the ad community is all the time working to optimise the crusade – putting off it from sites where it is not converting and weighting it more closely where the advertiser is getting a better ROI. Through these optimisation innovations, the ad community is in a position to charge higher prices for ads across its community, which then means higher eCPMs and payouts for its publishers. Ad exchanges provide a level platform where publishers, advertisers, and ad networks can all buy and sell ad space using a real time bidding system. Each impression is bid on separately and automatically to get the advertiser or ad community the lowest price available for the ad stock they want to buy, and to get publishers the highest price available for the ad space they are looking to sell.
Due to the big volume of ad stock accessible on these exchanges, prices are often very attractive to advertisers, whilst they still offer publishers a way of monetising any inventory that they weren’t capable of sell privately or via a more classic ad community.