Google AdSense has launched a new feature called Ad Placements which are “a specific groups of ad units, defined by you, on which an advertiser can place their ads.”
The new feature can be seen on your channels page after logging into AdSense. There is a message posted on the top which reads “NEW! We've improved custom channels – now, you have the option to enable any custom channel to be targeted by advertisers. You can also update any existing custom channels to allow advertiser targeting. Learn more about targetable custom channels.”
Google has also given details about working of Ad Placements:
1. You create a custom channel (for example, "Leaderboards" or "Sports"). Generate channel-specific code for the channel and use it to implement ads on your pages as you would with any custom channel.
2. If you choose to have the custom channel appear as an ad placement, you'll need to provide additional information about the ad location and type of page, as well as an accurate description of the placement.
3. When advertisers search for places to target their ads using site targeting, they'll see your placement and description as an option on which they can place their ads.